.gitignore

@@ -1,3 +1,7 @@
 .vscode
+deferred_planarity_test/bin
+make_graphs/bin
+make_graphs/test_graphs
+make_planar/bin
 test_area
-graph_datasets
+dpt

benchmark_results/north/.gitignore

@@ -1,7 +0,0 @@
-dpt_planarizer
-north.txt
-north_result.csv
-north_subset.txt
-ogdf_mps_fast
-output_north_dfs.txt
-output_north_fast.txt

benchmark_results/north/benchmark_north.bash

@@ -1,33 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-PROGRAM=$2
-
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/north/gml_non_planar/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    
-    # Run your program and capture its output
-    if [ "$PROGRAM" == "ogdf_mps_fast" ]; then
-        # do something if strings are equal
-        ./$PROGRAM "$INPUT_PATH$INPUT_FILE"
-    elif [ "$PROGRAM" == "dpt_planarizer" ]; then
-        # do something if strings are not equal
-        ./$PROGRAM "$INPUT_PATH$INPUT_FILE" 1000
-    fi
-
-
-done < $FILE_LIST

benchmark_results/rome/.gitignore

@@ -1,6 +0,0 @@
-dpt_planarizer
-ogdf_mps_fast
-output_rome_dfs.txt
-output_rome_fast.txt
-rome.txt
-rome_result.csv

benchmark_results/rome/benchmark_rome.bash

@@ -1,33 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-PROGRAM=$2
-
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/rome/gml_non_planar/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    
-    # Run your program and capture its output
-    if [ "$PROGRAM" == "ogdf_mps_fast" ]; then
-        # do something if strings are equal
-        ./$PROGRAM "$INPUT_PATH$INPUT_FILE"
-    elif [ "$PROGRAM" == "dpt_planarizer" ]; then
-        # do something if strings are not equal
-        ./$PROGRAM "$INPUT_PATH$INPUT_FILE" 1000
-    fi
-
-
-done < $FILE_LIST

benchmark_results/steinlib/.gitignore

@@ -1,9 +0,0 @@
-benchmark_steinlib.bash
-dpt_planarizer
-dpt_planarizer_random
-dpt_planarizer_wilson
-get_graph_char
-ogdf_mps_cactus
-ogdf_mps_fast
-output_steinlib_*
-steinlib.txt

data_process/.gitignore

@@ -1,3 +0,0 @@
-graphml_to_gml
-north_input.txt
-rome_input.txt

data_process/file_process_north.bash

@@ -1,26 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-echo "$FILE_LIST"
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/north/graphml/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    # Modify output path
-    OUTPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/north/gml/"$filename_stem".gml
-    
-    # Call your program with input and modified output paths
-    ./graphml_to_gml "$INPUT_PATH$INPUT_FILE" "$OUTPUT_PATH"
-done < $FILE_LIST

data_process/file_process_rome.bash

@@ -1,28 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-echo "$FILE_LIST"
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/rome/graphml/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    # Modify output path
-    OUTPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/rome/gml/"$filename_stem".gml
-
-    echo "$filename_stem"
-    
-    # Call your program with input and modified output paths
-    ./graphml_to_gml "$INPUT_PATH$INPUT_FILE" "$OUTPUT_PATH"
-done < $FILE_LIST

deferred_planarity_test/main.cpp

@@ -0,0 +1,60 @@
+//-----------------------------------------------------------------------------------
+// A simple code that test the MPS algorighm.
+//-----------------------------------------------------------------------------------
+
+#include "mps.h"
+#include <iostream>
+#include <cstdlib>
+#include <climits>
+#include <string>
+#include <algorithm>
+#include <iterator>
+#include <random>
+#include <vector>
+ 
+#include <ogdf/fileformats/GraphIO.h>
+
+using namespace std;
+
+int compute_removed_edge_size(string input_file, vector<int> post_order);
+
+int get_graph_size(string input_file) {
+    ogdf::Graph G;
+
+    // utilize OGDF readGML
+    if (!ogdf::GraphIO::read(G, input_file, ogdf::GraphIO::readGML)) {
+        std::cerr << "Could not read " << input_file << ".gml" << std::endl;
+    }
+
+    return G.numberOfNodes();
+}
+
+//-----------------------------------------------------------------------------------
+// Main function.
+//-----------------------------------------------------------------------------------
+
+
+int main(int argc, char* argv[]) {
+    string input_file = argv[1];
+    int num_runs = stoi(argv[2]);
+    // find the size of the graph here
+    int node_size = get_graph_size(input_file);
+    // generate order here
+    vector<int> post_order;
+    for (int i=0; i < node_size; ++i) {
+        post_order.push_back(i);
+    }
+
+    for (int i=0; i< num_runs; ++i) {
+        std::random_device rd;
+        std::mt19937 g(rd());
+    
+        std::shuffle(post_order.begin(), post_order.end(), g);
+        // print order
+        std::copy(post_order.begin(), post_order.end(), std::ostream_iterator<int>(std::cout, " "));
+        std::cout << std::endl;
+        std::cout << "Number of removed edges: " << compute_removed_edge_size(input_file, post_order) << std::endl;
+    }
+
+	return 0;
+}

deferred_planarity_test/mps.cpp

@@ -0,0 +1,736 @@
+//-----------------------------------------------------------------------------------
+// Implementation of a MPS algorithm via PC-tree.
+//-----------------------------------------------------------------------------------
+
+#include "mps.h"
+
+//Empty constructor
+maximal_planar_subgraph_finder::maximal_planar_subgraph_finder() {}
+
+//Destructor
+maximal_planar_subgraph_finder::~maximal_planar_subgraph_finder() {
+	for (int i = 0; i < _node_list.size(); ++i) delete _node_list[i];
+	for (int i = 0; i < _new_node_list.size(); ++i) delete _new_node_list[i];
+}
+
+node* 
+maximal_planar_subgraph_finder::get_new_node(node_type t) {
+	_new_node_list.push_back(new node(t));
+	return _new_node_list[_new_node_list.size()-1];
+}
+
+//Determine the post-order-list by a DFS-traversal.
+void 
+maximal_planar_subgraph_finder::postOrderTraversal() {
+	node::init_mark();
+	int postOrderID = 0;
+	for (int i = 0; i < _node_list.size(); ++i) {
+		if (!_node_list[i]->is_marked()) {
+			_node_list[i]->DFS_visit(_post_order_list, postOrderID);
+		}
+	}
+}
+
+//Set the post-order-list via given list
+void
+maximal_planar_subgraph_finder::set_post_order(vector<int> post_order) {
+    for (int i = 0; i < _node_list.size(); ++i) {
+        _node_list[i]->set_post_order_index(post_order[i]);
+    }
+}
+
+//Sort the adj-list of every node increasingly according to post-order-index.
+void
+maximal_planar_subgraph_finder::sort_adj_list() {
+	vector<vector<node*> > vecList;
+	vecList.resize(_post_order_list.size());
+	for (int i = 0; i < _post_order_list.size(); ++i) {
+		for (int j = 0; j < _post_order_list[i]->degree(); ++j) {
+			vecList[_post_order_list[i]->adj(j)->post_order_index()].push_back(_post_order_list[i]);
+		}
+	}
+	for (int i = 0; i < _post_order_list.size(); ++i) {
+		_post_order_list[i]->set_adj_list(vecList[i]);
+	}
+}
+
+//Determine edge-list, and back-edge-list.
+//Order the edges properly.
+void 
+maximal_planar_subgraph_finder::determine_edges() {
+	for (int i = 0; i < _post_order_list.size(); ++i) {
+		if (_post_order_list[i]->parent() == 0) continue;
+		_post_order_list[i]->set_1st_label(_post_order_list[i]->parent()->post_order_index());
+		_edge_list.push_back(pair<node*, node*> (_post_order_list[i]->parent(), _post_order_list[i]));
+	}
+	for (int i = 0; i < _post_order_list.size(); ++i) {
+		for (int j = 0; j < _post_order_list[i]->degree(); ++j) {
+			if (_post_order_list[i]->adj(j)->post_order_index() > i) break;
+			if (_post_order_list[i]->adj(j)->get_1st_label() == i) continue;
+			_back_edge_list.push_back(pair<node*, node*> (_post_order_list[i], _post_order_list[i]->adj(j)));
+			_is_back_edge_eliminate.push_back(false);
+		}
+	}
+	for (int i = 0; i < _post_order_list.size(); ++i) {
+		_post_order_list[i]->set_1st_label(INT_MAX);
+	}
+}
+
+//The main part of the whole algorithm: Back-edge-traversal
+void 
+maximal_planar_subgraph_finder::back_edge_traversal() {
+	node* i_node = 0;
+	node* current_node = 0;
+	for (int i = 0; i < _back_edge_list.size(); ++i) {
+		current_node = _back_edge_list[i].second;
+		i_node = _back_edge_list[i].first;
+		if (!back_edge_traversal(current_node, i_node->post_order_index())) _is_back_edge_eliminate[i] = true;
+	}
+}
+
+//sub-function for the for-loop of back_edge_traversal().
+bool maximal_planar_subgraph_finder::back_edge_traversal(node* traverse_node, int index) {
+	node* parent_node; //The next node to traverse.
+	//If the node has been deleted. 
+	if (traverse_node == 0 || traverse_node->get_2nd_label() == DELETED) {
+		return false;
+	}
+	//We have reached the i-node, stop.
+	if (traverse_node->post_order_index() == index) {
+		return true;
+	}
+	//Case 1
+	if (traverse_node->get_2nd_label() == NOT_VISITED) {
+		//1.1
+		if (traverse_node->get_1st_label() == INT_MAX) {
+			traverse_node->set_1st_label(index);
+			parent_node = traverse_node->parent();
+		}
+		//1.2
+		else if (traverse_node->get_1st_label() == index) {
+			return true;
+		}
+		//1.3
+		else if (traverse_node->get_1st_label() < index) {
+			parent_node = construct(traverse_node);
+			traverse_node->set_1st_label(index);
+		}
+	}
+	//Case 2: Find the top-tier c-node.
+	else {
+		node* my_c_node = find(traverse_node);
+		make_essential(traverse_node, my_c_node);
+		//2.1
+		if (my_c_node->get_1st_label() == index) {
+			parent_node = my_c_node;
+		}
+		//2.2
+		else if (my_c_node->get_1st_label() < index) {
+			node* my_c_node_2 = construct(my_c_node, traverse_node);
+			parent_node = my_c_node_2;
+		}
+		traverse_node->set_1st_label(index);
+		traverse_node->set_2nd_label(NOT_VISITED);
+	}
+	if (back_edge_traversal(parent_node, index)) {
+		if (parent_node != _post_order_list[index]) parent_node->add_child(traverse_node);
+		return true;
+	}
+	else {
+		eliminate(traverse_node);
+		return false;
+	}
+}
+
+//The p_node is originally a normal node in c_node's boundary cycle.
+//Now we transfer it to be an essential node by the following steps:
+//1. Create a replica-node of p_node to be representative of p_node in c_node.
+//2. Take out the p_node from c_node, and then set the parent of p_node to be c_node.
+//Note: We are not adding p_node to the c_node's children-list.
+void 
+maximal_planar_subgraph_finder::make_essential(node* p_node, node* c_node) {
+	node* sentinel = get_new_node(REPLICA_NODE);
+	node* n0 = p_node->neighbor(0);
+	node* n1 = p_node->neighbor(1);
+	sentinel->init_replica(p_node, c_node);
+	c_node->add_essential(sentinel);
+	sentinel->set_to_boundary_path(n0, n1);
+	sentinel->inherit_AE(p_node);
+	n0->set_neighbor(n0->get_next(p_node), sentinel);
+	n1->set_neighbor(n1->get_next(p_node), sentinel);
+	p_node->set_neighbor((node*)0, (node*)0);
+	p_node->set_parent(c_node);
+}
+
+//Find the top-tier c-node of the input node.
+//Note: We don't set the input node to be essential node of the top-tier c-node.
+//When terminated, the input node will be in the boundary cycle of top-tier c-node.
+node* maximal_planar_subgraph_finder::find(node* n) {
+	pair<pair<node*, node*>, pair<node*, node*> > boundary;
+	node* c_node_new = 0;
+	int c_node_size = 0;
+	node* return_node = 0;
+	if (n->parent() == 0) {
+		//If n is already a node in boundary cycle.
+		//Note: n must not be an essential node, otherwise it will never enter the function.
+		//Find the first(nearest to n) essential node.
+		boundary.first = parallel_search_sentinel(n, c_node_new);
+	}
+	else {
+		//If n is not a node in boundary cycle.
+		//It is in an Artificial edge.
+		//Trim it.
+		boundary = trim(n);
+		//Find the first(nearest to n) essential node.
+		boundary.first = parallel_search_sentinel(boundary.first.first, boundary.first.second, boundary.second.first, boundary.second.second, c_node_new);
+	}
+    //Find the c-node in the current hierachy .
+    //If it is top-tier, return it.
+	if (c_node_new != 0) return c_node_new;
+	c_node_new = (boundary.first).first->get_c_node();
+       
+	//If not, find the two nearest essential node, eliminate the rest nodes.
+	c_node_size = c_node_new->c_node_size();
+	boundary.second = count_sentinel_elimination(boundary.first, c_node_size);
+	//Go to the higher hierachy, and continue to find.
+	if (c_node_new->get_2nd_label() == ARTIFICIAL_EDGE) {
+		//A peculiar technic: 
+		//Remove all the children of c_node_new but the one that should remains(Let it be u).
+		//Remove all other essential nodes, pretend to be a c-node of size equals 2.
+		//Call find(u).
+		node* u = 0;
+		for (int i = 0; i < c_node_new->child_num(); ++i) {
+			if (node::is_same(boundary.first.first, c_node_new->child(i)) || node::is_same(boundary.second.first, c_node_new->child(i))) {
+				u = c_node_new->child(i);
+			}
+			else eliminate(c_node_new->child(i));
+		}
+		c_node_new->clear_children();
+		c_node_new->add_child(u);
+		c_node_new->clear_essential();
+		c_node_new->add_essential(boundary.first.first);
+		c_node_new->add_essential(boundary.second.first);
+		return_node = find(u);
+	}
+	else return_node = find(c_node_new);
+	//Merge the part of boundary cycle remains in current hierachy to the top-tier c-node.
+	merge(boundary, c_node_new);
+	return return_node;
+}
+
+//The list_node is a c-node. 
+//The boundary indicates the part of the boundary cycle of c-node needs to be merge to the higher hierachy.
+//Replace the list_node by boundary.
+//Set list_node to be DELETED.
+//Note: We do not eliminate anything in this function.
+void 
+maximal_planar_subgraph_finder::merge(pair<pair<node*, node*>, pair<node*, node*> > boundary, node* list_node) {
+	node* n0 = list_node->neighbor(0);
+	node* n1 = list_node->neighbor(1);
+	node* s0, * s0_prev;
+	node* s1, * s1_prev;
+	if (node::is_same(boundary.first.first, n0)) {
+		s0 = boundary.first.first;
+		s0_prev = boundary.first.second;
+		s1 = boundary.second.first;
+		s1_prev = boundary.second.second;
+	}
+	else {
+		s0 = boundary.second.first;
+		s0_prev = boundary.second.second;
+		s1 = boundary.first.first;
+		s1_prev = boundary.first.second;
+	}
+	if (s0_prev == s1 && s1_prev == s0) {
+	    n0->set_neighbor(n0->get_next(list_node), n1);
+	    n1->set_neighbor(n1->get_next(list_node), n0);
+	}
+	else {
+	    n0->set_neighbor(n0->get_next(list_node), s0_prev);
+	    n1->set_neighbor(n1->get_next(list_node), s1_prev);
+	    s0_prev->set_neighbor(s0_prev->get_next(s0), n0);
+	    s1_prev->set_neighbor(s1_prev->get_next(s1), n1);
+	}
+	//Inherit AE.
+	n0->inherit_AE(s0);
+	n1->inherit_AE(s1);
+	//Delete c-node
+	list_node->set_2nd_label(DELETED);
+}
+
+//Set u and its subtree to be DELETED.
+//If u has some AE, eliminate them.
+//We don't do anything about u's parent, neighborhood.(Only children are affected.)
+//If u is a p-node, we don't eliminate anything in the lower hierachy that corresponds to the same p-node.
+//If u is a c-node, we eliminate all nodes in u's boundary cycle.
+void 
+maximal_planar_subgraph_finder::eliminate(node* u) {
+	if (u->get_2nd_label() == DELETED) return;
+       u->set_2nd_label(DELETED);
+	if (u->type() == C_NODE) {
+		node* list_node = u->get_a_list_node();
+		node* n0, * n0_prev;;
+	    node* temp = 0;
+		n0 = list_node;
+	    n0_prev = list_node->neighbor(0);
+		while (true) {
+			eliminate(n0);
+			temp = n0;
+			n0 = n0->get_next(n0_prev);
+			n0_prev = temp;
+			if (n0 == list_node) break;
+		}
+	}
+	else if (u->type() == P_NODE) {
+		for (int i = 0; i < u->degree(); ++i) {
+			if (u->adj(i)->post_order_index() < u->post_order_index() && u->adj(i)->get_1st_label() == INT_MAX) eliminate(u->adj(i));
+		}
+	}
+	if (u->AE(0) != 0) eliminate(u->AE(0));
+	if (u->AE(1) != 0) eliminate(u->AE(1));
+	for (int i = 0; i < u->child_num(); ++i) {
+		eliminate(u->child(i));
+	}
+}
+
+//Eliminate the AE of(u,v)-link that points to u.(If exists)
+void 
+maximal_planar_subgraph_finder::eliminate_AE(node* u, node* v) {
+	int v_index = v->post_order_index();
+	if (u->AE(0) != 0 && u->AE(0)->get_1st_label() == v_index) {
+		eliminate (u->AE(0));
+		u->set_AE(0, 0);
+	}
+	if (u->AE(1) != 0 && u->AE(1)->get_1st_label() == v_index) {
+		eliminate (u->AE(1));
+		u->set_AE(1, 0);
+	}
+}
+
+//The input node u must not be c-node.
+//The traversed node is in the AE = (up <- down).
+//The returned boundary = [up, up_prev ..., down_prev, down].
+//Direction: up it higher than down.
+pair<pair<node*, node*>, pair<node*, node*> > 
+maximal_planar_subgraph_finder::trim(node* u) {
+	node* up = 0;
+	node* down = 0;
+	//Since we may do c-node extension in the future, we need to memorize next in order to deduce prev.
+	node* up_next = 0;
+	node* down_next = 0;
+	node* new_AE_root = 0;
+    //The index from small to large indicates the path that we traversed, note that u = node_list[0].
+	vector<node*> node_list;
+	node* curr = u;
+	node_list.push_back(u);
+	//Traverse upward.
+	while (true) {
+		curr = curr->parent();
+		if (curr->type() == AE_VIRTUAL_ROOT) {
+			up = curr->parent();
+			//case 1: We are in a newly created c-node.
+			//It has only one AE, and the two neighbor-pointer point to the same one.
+			if (up->neighbor(0) == up->neighbor(1)) {
+				down = up->neighbor(0);
+				up->set_neighbor(down, node_list[node_list.size()-1]);
+				down->set_neighbor(up, node_list[0]);
+				curr->remove_child(node_list[node_list.size()-1]);
+				//There's no other child, just delete the AE.
+				if (curr->child_num() == 0) {
+					up->set_AE(0, 0);
+					up->set_AE(1, 0);
+				}
+			}
+			//case 2: General case.
+			else {
+				if (up->neighbor(0)->post_order_index() == curr->get_1st_label()) down = up->neighbor(0);
+				else down = up->neighbor(1);
+				up->set_neighbor(up->get_next(down), node_list[node_list.size()-1]);
+				down->set_neighbor(down->get_next(up), node_list[0]);
+				curr->remove_child(node_list[node_list.size()-1]);
+				eliminate_AE(up, down);
+			}
+			break;
+		}
+		node_list.push_back(curr);
+	}
+	//Set the "downward" AE of node_list[0].
+	new_AE_root = get_new_node(AE_VIRTUAL_ROOT);
+	new_AE_root->init_AE(node_list[0]);
+	//Eliminate the children other than the path.
+	for (int i = 1; i < node_list.size(); ++i) {
+		for (int j = 0; j < node_list[i]->child_num(); ++j) {
+			if (node_list[i]->child(j) != node_list[i-1]) eliminate(node_list[i]->child(j));
+		}
+	}
+	//Set to the boundary path.
+	if (node_list.size() == 1) node_list[0]->set_to_boundary_path(up, down);
+	else {
+		node_list[0]->set_to_boundary_path(down, node_list[1]);
+		node_list[node_list.size()-1]->set_to_boundary_path(up, node_list[node_list.size()-2]);
+	    for (int i = 1; i < node_list.size()-1; ++i) {
+			node_list[i]->set_to_boundary_path(node_list[i-1], node_list[i+1]);
+		}
+	}
+	//Set the next of up and down.
+	up_next = up->get_next(node_list[node_list.size()-1]);
+	down_next = down->get_next(node_list[0]);
+	//Unfold the c-nodes in the node_list.
+	for (int i = 0; i < node_list.size(); ++i) {
+		if (node_list[i]->type() == C_NODE) c_node_extension(node_list[i]);
+	}
+	//Return the new boundary.
+	return pair<pair<node*, node*>, pair<node*, node*> > (pair<node*, node*>(up, up->get_next(up_next)), pair<node*, node*>(down, down->get_next(down_next)));
+}
+
+//The trim's sub-function.
+//The input c-node does not contain any children nor parent, but it has two neighbors, which is originally c-node's parent and one child.
+//If c-node's size equals 2, then we don't need to unfold it.
+//Otherwise, it must has size equals 3. 
+//And then we find that redundent essential node, and remove the nodes that need not remains.
+//Merge the remain part to the higher hierachy.
+void 
+maximal_planar_subgraph_finder::c_node_extension(node* c_node) {
+	//size == 2
+	if (c_node->c_node_size() == 2) return;
+	//size == 3
+	node* sentinel = 0;
+	for (int i = 0; i < c_node->c_node_size(); ++i) {
+		if (!node::is_same(c_node->essential(i), c_node->neighbor(0)) && !node::is_same(c_node->essential(i),  c_node->neighbor(1))) {
+			sentinel = c_node->essential(i);
+			break;
+		}
+	}
+	eliminate(sentinel);
+	//The two other essential nodes and their subsequent neighbor.
+	pair<node*, node*> sentinel_0; 
+	pair<node*, node*> sentinel_1;
+	node* n0, * n0_prev = sentinel;
+	node* n1, * n1_prev = sentinel;
+	node* temp = 0;
+	n0 = sentinel->neighbor(0);
+	n1 = sentinel->neighbor(1);
+	while (true) {//Toward the direction of n0.
+		if (n0->is_sentinel()) {//If we meet a essential node, stop, don't remove it.
+			sentinel_0 = pair<node*, node*> (n0, n0->get_next(n0_prev));
+			break;
+		}
+		eliminate(n0);
+		temp = n0;
+		n0 = n0->get_next(n0_prev);
+		n0_prev = temp;
+	}
+	while (true) {//Toward the direction of n0.
+		if (n1->is_sentinel()) {//If we meet a essential node, stop, don't remove it.
+			sentinel_1 = pair<node*, node*> (n1, n1->get_next(n1_prev));
+			break;
+		}
+		eliminate(n1);
+		temp = n1;
+		n1 = n1->get_next(n1_prev);
+		n1_prev = temp;
+	}
+
+	//Remember to remove the AE toward two essential nodes that is in the delete region. 
+	eliminate_AE(sentinel_0.first, sentinel_0.first->get_next(sentinel_0.second));
+	eliminate_AE(sentinel_1.first, sentinel_1.first->get_next(sentinel_1.second));
+	//Reset the neighborhood of two essential nodes.
+	sentinel_0.first->set_neighbor(sentinel_1.first, sentinel_0.second);
+	sentinel_1.first->set_neighbor(sentinel_0.first, sentinel_1.second);
+	//Merge to upper boundary cycle.
+	merge(pair<pair<node*, node*>, pair<node*, node*> >(sentinel_0, sentinel_1), c_node);
+}
+
+//u is a normal p-node.
+//We'll do the work of elimination, and renewing of children-list.
+void 
+maximal_planar_subgraph_finder::recursively_shaving(node* u) { 
+	node* parent_node = 0;
+	node* node_x = 0;
+	pair<node*, node*> new_two_child;
+	vector<node*> new_child_list;
+	//p-node
+	if (u->type() == P_NODE) {
+		for (int i = 0; i < u->child_num(); ++i) recursively_shaving(u->child(i));
+	}
+	//c-node
+	else {
+		//We don't need to shave if u has only one child.
+		if (u->child_num() == 1) {
+			recursively_shaving(u->child(0));
+			return;
+		}
+		//More than one child.
+		parent_node = u->parent();
+		//Find node_x, and shave it.
+		for (int i = 0; i < u->c_node_size(); ++i) {
+			if (node::is_same(u->essential(i), parent_node)) {
+				node_x = u->essential(i);
+				new_two_child = shave(node_x);
+				break;
+			}
+		}
+		//Reset children-list and essential node.
+		for (int i = 0; i < u->child_num(); ++i) {
+			if (node::is_same(u->child(i), new_two_child.first) || node::is_same(u->child(i), new_two_child.second)) new_child_list.push_back(u->child(i));
+			else eliminate(u->child(i));
+		}
+		u->clear_children();
+		u->clear_essential();
+		u->add_essential(node_x);
+		u->add_essential(new_two_child.first);
+		u->add_essential(new_two_child.second);
+		u->add_child(new_child_list[0]);
+		u->add_child(new_child_list[1]);
+		for (int i = 0; i < u->child_num(); ++i) recursively_shaving(u->child(i));
+	}
+}
+
+//In this function, we only deal with inner part of c-node.
+//x,y,z are essential nodes, let y,z be x's nearest essential nodes in w's boundary cycle.
+//Anything outside [x,y], and[x,z] will be eliminated.
+//Definition of y_prev, z_prev: ..., y, y_prev, ..., x, ..., z_prev, z, ...
+//Return pair = (y,z). Note: What we return is the replica-node in the inner part of c-node.
+//The work of deleting children will be done by recursively_shaving().
+pair<node*, node*> 
+maximal_planar_subgraph_finder::shave(node* x) {
+    //c-node.
+	node* c_node = x->get_c_node(); 
+    //No need to shave if child_num == 1.
+	if (c_node->child_num() == 1) return pair<node*, node*>((node*)0, (node*)0); 
+    //sentinel_1 = (y, y_prev). Note: At this time, c-node must has type equals ARTIFICIAL_EDGE, so no problem here.
+	pair<node*, node*> sentinel_1 = parallel_search_sentinel(x, c_node);
+	//sentinel_2 = (z, z_prev). Same as above.
+	pair<node*, node*> sentinel_2 = count_sentinel_elimination(sentinel_1, c_node->child_num());
+	return pair<node*, node*>(sentinel_1.first, sentinel_2.first);
+}
+
+//Use parallel_search to find essential nodes. Return (essential nodes that we find, its prev).
+//x is not in the searching region.
+//If the c-node found is top-tier, then set all the nodes during searching a pointer to c-node, set c to be that c-node, and return pair be all null.
+pair<node*, node*> 
+maximal_planar_subgraph_finder::parallel_search_sentinel(node* x, node* &c) {
+	node* n0, * n0_prev = x;
+	node* n1, * n1_prev = x;
+	n0 = x->neighbor(0);
+	n1 = x->neighbor(1);
+	return parallel_search_sentinel(n0, n0_prev, n1, n1_prev, c);
+}
+
+//Another version of parallel search: n0, n0_prev, ..., n1_prev, n1
+//searching region = (...n0] [n1...). Find the nearest essential node.
+//return (essential nodes that we find, its prev).
+pair<node*, node*> 
+maximal_planar_subgraph_finder::parallel_search_sentinel(node* n0, node* n0_prev, node* n1, node* n1_prev, node* & c) {
+	node* temp = 0;
+	vector<node*> traversed;
+	while (true) {
+		//If c-node is top-tier.   
+        //note: If c points to a c-node traversed in some previous iteration, then it must not be top-tier, so it'll not pass the if-condition.
+		if (n0->get_c_node() != 0 && n0->get_c_node()->get_2nd_label() == NOT_VISITED) {
+			c = n0->get_c_node();
+			break;
+		}
+		if (n1->get_c_node() != 0 && n1->get_c_node()->get_2nd_label() == NOT_VISITED) {
+			c = n1->get_c_node();
+			break;
+		}
+		//If an essential-node found.
+		if (n0->is_sentinel()) return pair<node*, node*>(n0, n0_prev);
+		if (n1->is_sentinel()) return pair<node*, node*>(n1, n1_prev);
+		//Just a normal node..
+		traversed.push_back(n0);
+		traversed.push_back(n1);
+		temp = n0;
+		n0 = n0->get_next(n0_prev);
+		n0_prev = temp;
+		temp = n1;
+		n1 = n1->get_next(n1_prev);
+		n1_prev = temp;
+	}
+
+	//If the c-node found is top-tier, then assign all the traversed node a pointer to c-node.
+	for (int i = 0; i < traversed.size(); ++i) traversed[i]->set_c_node(c);
+	return pair<node*, node*>((node*)0, (node*)0);
+}
+
+// sentinel_1= (y, y_prev)
+// return pair = (z, z_prev)
+// ..., y_prev, y,[ ...(contains num_sentinel-2 essential nodes)...], z, z_prev, ... : eliminate the [...] part.
+// Which means, num_sentinel = Number of essential nodes in the region [y, z].
+// Note: y, z(Of course, and their prev,) will not be eliminated.
+// Note: All the node that correspond to the same one as deleted node in higher hierachy will not be affected.
+// The boundary cycle of c-node will be re-connected, AE be properly handled.
+// Do nothing outside the c-node.
+pair<node*, node*> maximal_planar_subgraph_finder::count_sentinel_elimination(pair<node*, node*> sentinel_1, int num_sentinel) {
+	pair<node*, node*> sentinel_2; //(z, z_prev)
+	int count = 1;//Count the essential nodes traversed.
+	node* n0 = sentinel_1.first->get_next(sentinel_1.second), * n0_prev = sentinel_1.first;//Going one step further.
+	node* temp = 0;
+	while (true) {
+		if (n0->is_sentinel()) {
+			++count;//counter
+			if (count == num_sentinel) {//We have reached y. Note: We will not eleminate y.
+				sentinel_2.first = n0;
+				sentinel_2.second = n0->get_next(n0_prev);
+				break;
+			}
+		}
+		eliminate(n0);
+		temp = n0;
+		n0 = n0->get_next(n0_prev);
+		n0_prev = temp;
+	}
+	//Remember to eliminate AE toward two essential nodes that is in the deleted region.
+	eliminate_AE(sentinel_2.first, sentinel_2.first->get_next(sentinel_2.second));
+	eliminate_AE(sentinel_1.first, sentinel_1.first->get_next(sentinel_1.second));
+	//Reset neighborhood of two essential nodes.
+	sentinel_2.first->set_neighbor(sentinel_1.first, sentinel_2.second);
+	sentinel_1.first->set_neighbor(sentinel_2.first, sentinel_1.second);
+	return sentinel_2;
+}
+
+//Used when u has label equals <i, 0>, i<j, where j is current iteration. 
+//Create a c-node with u being first essential node, and i being head. Return it.
+//We'll done the parent-linke of (u -> c-node -> node_i).
+//We don't create child-link here.
+//Default label of newly contructed c-node is (INT_MAX, NOT_VISITED).
+node*
+maximal_planar_subgraph_finder::construct(node* u) {
+	//Basic works.
+	int i_label = u->get_1st_label();
+	node* node_i = _post_order_list[u->get_1st_label()];
+	parenting_labeling_shaving(u, node_i);
+
+	//Get some new nodes.
+	node* i_sentinel = get_new_node(REPLICA_NODE);
+	node* u_sentinel = get_new_node(REPLICA_NODE);
+	node* new_c_node = get_new_node(C_NODE);
+	node* new_AE_root = get_new_node(AE_VIRTUAL_ROOT);
+
+	//Setting of replica-nodes.
+	i_sentinel->init_replica(node_i, new_c_node);
+	u_sentinel->init_replica(u, new_c_node);
+	for (int i = 0; i < u->child_num(); ++i) {
+		u_sentinel->add_child(u->child(i));
+	}
+	new_AE_root->init_AE(u_sentinel);
+
+	//Neighborhood setting of replica-nodes in c-node.
+	i_sentinel->set_to_boundary_path(u_sentinel, u_sentinel);
+	u_sentinel->set_to_boundary_path(i_sentinel, i_sentinel);
+
+	//Default label of c-node.
+	new_c_node->set_1st_label(INT_MAX);
+	new_c_node->set_2nd_label(NOT_VISITED);
+
+	//Set essential node of c-node.
+	new_c_node->add_essential(i_sentinel);
+	new_c_node->add_essential(u_sentinel);
+
+	//Parenting
+	new_c_node->set_parent(node_i);
+	u->set_parent(new_c_node);
+
+	//Clear children-list of u_node. (which has benn transfered to AE inside c-node.)
+	u->clear_children();
+
+	return new_c_node;
+	}
+
+//The case when the first explored node is c-node (The input parameter c). 
+//The p-node that trigger c(The input parameter p), has p->c parent-link already, and p is essential(not essential before triggered).
+//But we don't have c->p child-link yet.
+//We are not going to establish that child-link in this function. (Will be done in BET's main loop.)
+//Set c to be DELETED.
+node* 
+maximal_planar_subgraph_finder::construct(node* c, node* p) {
+	//Basic works.
+	int i_label = c->get_1st_label();
+	node* node_i = _post_order_list[c->get_1st_label()];
+	parenting_labeling_shaving(p, node_i);
+	//note: Now, c must have exactly two children left, and c has a parent-link to p, p has achild link to c, too. 
+	//Remember to handle them later.
+
+	//Get some new nodes.
+	node* i_sentinel = get_new_node(REPLICA_NODE);
+	node* new_c_node = get_new_node(C_NODE);
+	i_sentinel->init_replica(node_i, new_c_node);
+
+	//Strategy: Build thisboundary cycle first: (i, child(0), c, child(1), i).
+	//And then find the two replica-node corresponding to the two children in c, and merge.
+	node* ch0 = c->child(0);
+	node* ch1 = c->child(1);
+	node* AE_root_0 = get_new_node(AE_VIRTUAL_ROOT);
+	node* AE_root_1 = get_new_node(AE_VIRTUAL_ROOT);
+	AE_root_0->init_AE(ch0);
+	AE_root_1->init_AE(ch1);
+	i_sentinel->set_to_boundary_path(ch0, ch1);
+	ch0->set_to_boundary_path(i_sentinel, c);
+	ch1->set_to_boundary_path(i_sentinel, c);
+	c->set_to_boundary_path(ch0, ch1);
+		
+	//find the boundary in c, merge!
+	node* sent_0;
+	node* sent_1;
+	node* sent_p;
+	for (int i = 0; i < c->c_node_size(); ++i) {
+		if (node::is_same(c->essential(i), ch0)) sent_0 = c->essential(i);
+		else if (node::is_same(c->essential(i), ch1)) sent_1 = c->essential(i);
+		else if (node::is_same(c->essential(i), p)) sent_p = c->essential(i);
+	}
+	merge(pair<pair<node*, node*>, pair<node*, node*> > (pair<node*, node*>(sent_0, sent_0->get_next(sent_1)), pair<node*, node*>(sent_1, sent_1->get_next(sent_0))), c);
+
+	//Set essential-node of c-node.
+	new_c_node->add_essential(i_sentinel);
+	new_c_node->add_essential(sent_p);
+
+	//Default label of c-node.
+	new_c_node->set_1st_label(INT_MAX);
+	new_c_node->set_2nd_label(NOT_VISITED);
+
+	//Parenting.
+	new_c_node->set_parent(node_i);
+
+	//p-node, p_sent.
+	sent_p->set_c_node(new_c_node);
+	p->clear_children();
+	p->set_parent(new_c_node);
+
+	//Delete c-node
+	c->set_2nd_label(DELETED);
+
+	return new_c_node;
+}
+
+//Some basic works in constructing c-node.
+//u is the first explored node in the newly constructed c-node.
+//In the case of newly constructed c-node itself is c-node, u will be the p-node that trigger the c-node.
+//And in this case, p->c parent-link has been established, but c->p child-link not.
+void 
+maximal_planar_subgraph_finder::parenting_labeling_shaving(node* u, node* node_i) {
+	//reverse parent-children relation in [u, node_i] as following. 
+	//(u-> ... ->y->i) -> (u<- ... <-y , i).
+	vector<node*> u_i_path;
+	u_i_path.push_back(u);
+	while (true) {
+		u_i_path.push_back(u_i_path[u_i_path.size()-1]->parent());
+		if (u_i_path[u_i_path.size()-1] == node_i) break;
+	}
+	for (int i = 0; i < u_i_path.size()-2; ++i) {
+		u_i_path[i]->add_child(u_i_path[i+1]);
+		u_i_path[i+1]->set_parent(u_i_path[i]);
+	}
+	for (int i = 0; i < u_i_path.size()-2; ++i) {
+		for (int j = 0; j < u_i_path[i+1]->child_num(); ++j) {
+			if (u_i_path[i+1]->child(j) == u_i_path[i]) {
+				u_i_path[i+1]->remove_child(j);
+			}
+		}
+	}
+	u_i_path[0]->set_parent(0);
+
+	//BFS-traversal, all labeled to <i,1>, and then shave the c-node.
+	u->recursively_labeling();
+	recursively_shaving(u);
+}

deferred_planarity_test/mps.h

@@ -0,0 +1,180 @@
+//-----------------------------------------------------------------------------------
+// Header for modules: mps.cpp, mps_test.cpp, node.cpp.
+//-----------------------------------------------------------------------------------
+
+#ifndef _MPS_H
+#define _MPS_H
+
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <utility>
+#include <climits>
+
+using namespace std;
+
+class node;
+class maximal_planar_subgraph_finder;
+
+enum label {
+	NOT_VISITED = 0,
+	ARTIFICIAL_EDGE = 1,
+	BOUNDARY_PATH = 2,
+	DELETED = 3
+};
+
+enum node_type {
+	P_NODE = 0,
+	C_NODE = 1,
+	REPLICA_NODE = 2,
+	AE_VIRTUAL_ROOT = 3
+};
+
+class node
+{
+public:
+	//CONSTRUCTOR
+	node(node_type t);
+
+	//DESTRUCTOR
+	~node() {}
+
+	//TYPE, ID, INDEX
+    node_type type();
+	int post_order_index();
+	void set_id(int i);
+	void set_post_order_index(int i);
+	void recursively_labeling();
+	int node_id();
+
+	//DFS-TREE
+	void add_adj(node* n);
+	int degree();
+	node* adj(int i);
+	void set_adj_list(vector<node*> vec);
+	void DFS_visit(vector<node*> &dfsList, int &index);
+
+	//PARENT-CHILDREN
+	void set_parent(node* n) ;
+	node* parent();
+	int child_num();
+	node* child(int i);
+	void add_child(node* n);
+	void clear_children();
+	void remove_child(int i);
+	void remove_child(node* n);
+	vector<node*>* get_children_list();
+
+	//BOUNDARY_PATH
+	void set_to_boundary_path(node* n0, node* n1);
+	void set_neighbor(int i, node* n);
+	void set_neighbor(node* u, node* v);
+	node* neighbor(int i);
+	node* get_next(node* prev);
+
+	//ARTIFICIAL EDGE
+	node* AE(int i);
+	void set_AE(int i, node* j);
+	void add_AE(node* j);
+	void inherit_AE(node* u);
+	void init_AE(node* u);
+
+	//REPLICA
+	node* original_node();
+	node* get_c_node();
+	void set_c_node(node* c);
+	bool is_sentinel();
+	static bool is_same(node* n1, node* n2);
+	void init_replica(node* u, node* c);
+
+	//LABELING
+	void set_1st_label(int i);
+	void set_2nd_label(label i);
+	int get_1st_label();
+	label get_2nd_label();
+
+	//C-NODE
+	node* get_a_list_node();
+	int c_node_size();
+	node* essential(int i);
+	void clear_essential();
+	void add_essential(node* u);
+
+	//MARK
+	void mark();
+	static void init_mark();
+	void un_mark();
+	bool is_marked();
+
+private:
+	//Basic information.
+	node_type _type;
+	pair<int, label> _label;
+
+	//Information about neighborhood.
+	node* _neighbor[2];
+	node* _AE_root[2];
+
+	//Information about higher hierarchy.
+	node* _original_node; 
+    node* _c_node;
+
+	//Information about parent-children relation.
+	node* _parent;
+	vector<node*> _children;
+
+	//Information about about p-nodes in DFS-tree
+	vector<node*> _adj_list;
+	int _post_order_index;
+	int _node_id;
+
+	//List of essential nodes in c-node
+	vector<node*> _essential_list;
+
+	//Mark
+	int _mark;
+	static int _ref_mark;
+};
+
+class maximal_planar_subgraph_finder
+{
+public:
+	maximal_planar_subgraph_finder();
+	~maximal_planar_subgraph_finder();
+	int find_mps(string input_file);
+	int compute_removed_edge_size(string input_file, vector<int> post_order);
+	node* get_new_node(node_type t);
+    void read_from_gml(string input_file);
+	int output_removed_edge_size();
+	void postOrderTraversal();
+    void set_post_order(vector<int> post_order);
+	void sort_adj_list();
+	void determine_edges();
+	void back_edge_traversal();
+	bool back_edge_traversal(node* traverse_node, int index);
+	void make_essential(node* p_node, node* c_node);
+	node* find(node* n);
+	void merge(pair<pair<node*, node*>, pair<node*, node*> > boundary, node* list_node);
+	void eliminate(node* u);
+	void eliminate_AE(node* u, node* v);
+	pair<pair<node*, node*>, pair<node*, node*> > trim(node* u);
+	void c_node_extension(node* c_node);
+	void recursively_shaving(node* u);
+	pair<node*, node*> shave(node* x);
+	pair<node*, node*> parallel_search_sentinel(node* x, node* &c);
+	pair<node*, node*> parallel_search_sentinel(node* n0, node* n0_prev, node* n1, node* n1_prev, node* & c);
+	pair<node*, node*> count_sentinel_elimination(pair<node*, node*> sentinel_1, int num_sentinel);
+	node* construct(node* u);
+	node* construct(node* c, node* p);
+	void parenting_labeling_shaving(node* u, node* node_i) ;
+
+private:
+	vector<node*> _node_list; //List of nodes input.
+	vector<pair<node*, node*> > _edge_list; // Edges in DFS-tree. These edges must be contained in the maximal planar subgraph that we found.
+	vector<node*> _post_order_list; //The sorted version (increasing with post-order-index) of _node_list.
+	vector<pair<node*, node*> > _back_edge_list; // Edges other than that in DFS-tree. (The first node's index is higher than the second's.)
+	vector<bool> _is_back_edge_eliminate; //Record that if the back-edge has been eliminated or not.
+	vector<node*> _new_node_list; //Newly added nodes.
+};
+
+#endif

deferred_planarity_test/mps_test.cpp

@@ -0,0 +1,78 @@
+//-----------------------------------------------------------------------------------
+// Implementation of a MPS algorithm via PC-tree.
+//-----------------------------------------------------------------------------------
+
+#include "mps.h"
+#include <ogdf/fileformats/GraphIO.h>
+
+//-----------------------------------------------------------------------------------
+// Finding MPS
+//-----------------------------------------------------------------------------------
+int find_mps(string input_file) {
+	maximal_planar_subgraph_finder m;
+	return m.find_mps(input_file);
+}
+
+int compute_removed_edge_size(string input_file, vector<int> post_order) {
+    maximal_planar_subgraph_finder m;
+    return m.compute_removed_edge_size(input_file, post_order);
+}
+
+int maximal_planar_subgraph_finder::find_mps(string input_file) {
+	read_from_gml(input_file);
+	postOrderTraversal();
+	sort_adj_list();
+	determine_edges();
+	back_edge_traversal();
+	return output_removed_edge_size();
+}
+
+
+int maximal_planar_subgraph_finder::compute_removed_edge_size(string input_file, vector<int> post_order) {
+	read_from_gml(input_file);
+    set_post_order(post_order);
+	sort_adj_list();
+	determine_edges();
+	back_edge_traversal();
+	return output_removed_edge_size();
+}
+
+//-----------------------------------------------------------------------------------
+// Imput, output
+//-----------------------------------------------------------------------------------
+
+
+// read input file of gml format
+void maximal_planar_subgraph_finder::read_from_gml(string input_file) {
+    ogdf::Graph G;
+
+    // utilize OGDF readGML
+    if (!ogdf::GraphIO::read(G, input_file, ogdf::GraphIO::readGML)) {
+        std::cerr << "Could not read " << input_file << ".gml" << std::endl;
+    }
+
+    // create nodes
+	for (int i = 0; i < G.numberOfNodes(); ++i) {
+		_node_list.push_back(new node(P_NODE));
+		_node_list[i]->set_id(i);
+	}
+
+    // create edges
+    for (ogdf::edge e : G.edges) {
+        ogdf::node source = e->source();
+        ogdf::node target = e->target();
+        _node_list[source->index()]->add_adj(_node_list[target->index()]);
+        _node_list[target->index()]->add_adj(_node_list[source->index()]);
+    }
+}
+
+
+
+//Output a maximal planar subgraph in the same format as input.
+int maximal_planar_subgraph_finder::output_removed_edge_size() {
+    int sum = 0;
+    for (int i = 0; i < _back_edge_list.size(); ++i) {
+		if (_is_back_edge_eliminate[i]) ++sum; 
+    }
+    return sum;
+}

deferred_planarity_test/node.cpp

@@ -0,0 +1,241 @@
+//-----------------------------------------------------------------------------------
+// Implementation of a MPS algorithm via PC-tree.
+//-----------------------------------------------------------------------------------
+
+#include "mps.h"
+
+//-----------------------------------------------------------------------------------
+// CONSTRUCTOR
+//-----------------------------------------------------------------------------------
+node::node(node_type t) {
+	_type = t;
+	_label = pair<int, label>(INT_MAX, NOT_VISITED);
+	_neighbor[0] = _neighbor[1] = 0;
+	_AE_root[0] = _AE_root[1]  = 0;
+	_original_node = 0; 
+    _c_node = 0;
+	_parent = 0;
+	_post_order_index = INT_MAX;
+	_node_id = INT_MAX;
+	_mark = 0;
+}
+
+//-----------------------------------------------------------------------------------
+// TYPE, ID, INDEX
+//-----------------------------------------------------------------------------------
+node_type node::type() {return _type;}
+
+int node::post_order_index() {return _post_order_index;}
+
+void node::set_id(int i) {_node_id = i;}
+
+void node::set_post_order_index(int i) {_post_order_index = i;}
+
+//Only used when consturcting c-node
+//The first node calling this function would not be labeled.
+void node::recursively_labeling() {		
+	for (int i = 0; i < _children.size(); ++i) {
+		_children[i]->_label.second = ARTIFICIAL_EDGE;
+		_children[i]->recursively_labeling();
+	} 
+}
+
+int node::node_id() {return _node_id;}
+
+//-----------------------------------------------------------------------------------
+// DFS-TREE
+//-----------------------------------------------------------------------------------
+void node::add_adj(node* n) {_adj_list.push_back(n);}
+
+int node::degree() {return _adj_list.size();}
+
+node* node::adj(int i) {return _adj_list[i];}
+
+void node::set_adj_list(vector<node*> vec) {_adj_list = vec;}
+
+void node::DFS_visit(vector<node*> &dfsList, int &index) {
+	mark();
+	for (int i = 0; i < _adj_list.size(); ++i) {
+		if (!_adj_list[i]->is_marked()) {
+			_adj_list[i]->_parent = this;
+			_adj_list[i]->DFS_visit(dfsList, index);
+		}
+	}
+	set_post_order_index(index);
+	dfsList.push_back(this);
+	++index;
+}
+
+//-----------------------------------------------------------------------------------
+// PARENT-CHILDREN
+//-----------------------------------------------------------------------------------
+int node::child_num() {return _children.size();}
+
+node* node::child(int i) {return _children[i];}
+
+node* node::parent() {return _parent;}
+
+void node::clear_children() {
+	_children.clear();
+}
+
+void node::remove_child(int i) {
+	_children[i] = _children[_children.size()-1];
+	_children.resize(_children.size()-1);
+}
+
+void node::remove_child(node* n) {
+	for (int i = 0; i < _children.size(); ++i) {
+	    if (_children[i] == n) {
+			_children[i] = _children[_children.size()-1];
+	        _children.resize(_children.size()-1);
+		}
+	}
+}
+
+void node::add_child(node* n) {
+	_children.push_back(n);
+}
+
+vector<node*>* node::get_children_list() {
+	vector<node*>* ptr = new vector<node*>(_children);
+	return ptr;
+}
+
+void node::set_parent(node* n) {
+	_parent= n;
+}
+
+//-----------------------------------------------------------------------------------
+// BOUNDARY_PATH
+//-----------------------------------------------------------------------------------
+void node::set_to_boundary_path(node* n0, node* n1) {
+	_parent = 0;
+	_children.clear();
+	_neighbor[0] = n0;
+	_neighbor[1] = n1;
+	set_2nd_label(BOUNDARY_PATH);
+}
+
+node* node::get_next(node* prev) {
+	if (_neighbor[0] != prev) return _neighbor[0];
+	else return _neighbor[1];
+}
+
+node* node::neighbor(int i) {return _neighbor[i];}
+
+void node::set_neighbor(int i, node* n) {_neighbor[i] = n;}
+
+void node::set_neighbor(node* u, node* v) {
+	_neighbor[0] = u;
+	_neighbor[1] = v;
+}
+
+//-----------------------------------------------------------------------------------
+// ARTIFICIAL EDGE
+//-----------------------------------------------------------------------------------
+node* node::AE(int i) {return _AE_root[i];}
+
+void node::set_AE(int i, node* j) {
+	_AE_root[i] = j;
+	if (j != 0) j->set_parent(this);
+} 
+
+void node::add_AE(node* j) {
+	if (j == 0) return;
+	if (_AE_root[0] == 0) set_AE(0, j);
+	else if (_AE_root[1] == 0) set_AE(1, j);
+}
+
+//Inherit u's artificial edge.
+void node::inherit_AE(node* u) {
+	if (u->_AE_root[0] != 0) add_AE(u->_AE_root[0]);
+	if (u->_AE_root[1] != 0) add_AE(u->_AE_root[1]);
+	u->_AE_root[0] = u->_AE_root[1] = 0;
+}
+
+//Set itself to be an AE-root-node in u.
+//Inherite u's chilren-list.
+//Do nothing if u does not have any children.
+void node::init_AE(node* u) {
+	if (u->child_num() == 0) return;
+	_children = u->_children;
+	u->clear_children();
+	for (int i = 0; i < _children.size(); ++i) {
+		_children[i]->set_parent(this);
+	}
+	set_parent(u);
+	set_1st_label(_children[0]->get_1st_label());
+	set_2nd_label(ARTIFICIAL_EDGE);
+	u->add_AE(this);
+}
+
+//-----------------------------------------------------------------------------------
+// REPLICA
+//-----------------------------------------------------------------------------------
+node* node::original_node() {return _original_node;}
+
+node* node::get_c_node() {return _c_node;}
+
+void node::set_c_node(node* c) {_c_node = c;}
+
+bool node::is_sentinel() {return type() == REPLICA_NODE;} 
+
+//Check if n1 and n2 correspond to the same node
+bool node::is_same(node* n1, node* n2) {
+	node* s1 = (n1->type() == REPLICA_NODE)? n1->original_node() : n1;
+	node* s2 = (n2->type() == REPLICA_NODE)? n2->original_node() : n2;
+	return s1 == s2;
+}
+
+//Set itself to be a replica-node of u in c.
+//Only inherit some basic setting, not including info about neighborhood.
+void node::init_replica(node* u, node* c) {
+	set_post_order_index(u->post_order_index());
+	set_2nd_label(BOUNDARY_PATH);
+	_original_node = (u->type() == REPLICA_NODE)? u->original_node() : u;
+	_c_node = c;
+}
+
+//-----------------------------------------------------------------------------------
+// LABELING
+//-----------------------------------------------------------------------------------
+void node::set_1st_label(int i) {_label.first = i;}
+
+void node::set_2nd_label(label i) {_label.second = i;}
+
+int node::get_1st_label() {return _label.first;}
+
+label node::get_2nd_label() {return _label.second;}
+
+//-----------------------------------------------------------------------------------
+// C-NODE
+//-----------------------------------------------------------------------------------
+node* node::get_a_list_node() {
+	return _essential_list[0];
+}
+
+int node::c_node_size() {
+	return _essential_list.size();
+}
+
+node* node::essential(int i) {
+	return _essential_list[i];
+}
+
+void node::clear_essential() {_essential_list.clear();}
+
+void node::add_essential(node* u) {_essential_list.push_back(u);}
+
+//-----------------------------------------------------------------------------------
+// MARK
+//-----------------------------------------------------------------------------------
+void node::mark() {_mark = _ref_mark;}
+
+void node::init_mark() {++_ref_mark;}
+
+void node::un_mark() {_mark = 0;}
+
+bool node::is_marked() {return _mark == _ref_mark;}
+
+int node::_ref_mark = 1;

find_non_planar/.gitignore

@@ -1,4 +0,0 @@
-north_gml_input.txt
-ogdf_test_planar
-rome_gml_input.txt
-steinlib_gml_input.txt

find_non_planar/find_non_planar_north.bash

@@ -1,32 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-echo "$FILE_LIST"
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/north/gml/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    # Modify output path
-    OUTPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/north/gml_non_planar/
-    
-    # Run your program and capture its output
-    output=$(./ogdf_test_planar "$INPUT_PATH$INPUT_FILE")
-
-    # Check the output and perform actions accordingly
-    if [ "$output" -eq 0 ]; then
-        # it is not planar, copy to folder
-        cp "$INPUT_PATH$INPUT_FILE" "$OUTPUT_PATH$INPUT_FILE"
-    fi
-done < $FILE_LIST

find_non_planar/find_non_planar_rome.bash

@@ -1,34 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-echo "$FILE_LIST"
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/rome/gml/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    # Modify output path
-    OUTPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/rome/gml_non_planar/
-    
-    # Run your program and capture its output
-    output=$(./ogdf_test_planar "$INPUT_PATH$INPUT_FILE")
-
-    echo "$filename_stem"
-
-    # Check the output and perform actions accordingly
-    if [ "$output" -eq 0 ]; then
-        # it is not planar, copy to folder
-        cp "$INPUT_PATH$INPUT_FILE" "$OUTPUT_PATH$INPUT_FILE"
-    fi
-done < $FILE_LIST

find_non_planar/find_non_planar_steinlib.bash

@@ -1,34 +0,0 @@
-#!/bin/bash
-
-FILE_LIST=$1
-
-echo "$FILE_LIST"
-
-# Check if file_list.txt exists
-if [ ! -f $FILE_LIST ]; then
-    echo "input file not found!"
-    exit 1
-fi
-
-INPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/steinlib/data/
-
-# Read file paths from file_list.txt
-while IFS= read -r INPUT_FILE; do
-    # Extract filename stem
-    filename=$(basename -- "$INPUT_FILE")
-    filename_stem="${filename%.*}"
-    
-    # Modify output path
-    OUTPUT_PATH=/home/richard/Projects/06_research/maximum_planar_subgraph/benchmark_data/graph_datasets/steinlib/gml_non_planar/
-    
-    # Run your program and capture its output
-    output=$(./ogdf_test_planar "$INPUT_PATH$INPUT_FILE")
-
-    echo "$filename_stem"
-
-    # Check the output and perform actions accordingly
-    if [ "$output" -eq 0 ]; then
-        # it is not planar, copy to folder
-        cp "$INPUT_PATH$INPUT_FILE" "$OUTPUT_PATH$INPUT_FILE"
-    fi
-done < $FILE_LIST

make_graphs/.gitignore

@@ -1,2 +0,0 @@
-bin
-test_graphs

make_planar/.gitignore

@@ -1 +0,0 @@
-bin

make_planar/get_graph_characteristics.cpp

@@ -1,26 +0,0 @@
-/* This code converts GraphML to gml
- * 
- */
-#include <ogdf/fileformats/GraphIO.h>
-
-#include <iostream>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string input_file = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, input_file, GraphIO::readGML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-    std::cout <<  G.numberOfNodes() << ", " << G.numberOfEdges() << std::endl;
-    
-
-    return 0;
-}

make_planar/graphml_to_gml.cpp

@@ -1,27 +0,0 @@
-/* This code converts GraphML to gml
- * 
- */
-#include <ogdf/fileformats/GraphIO.h>
-
-#include <iostream>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string input_file = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, input_file, GraphIO::readGraphML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-    string output_file = argv[2];
-    GraphIO::write(G, output_file, GraphIO::writeGML);
-    
-
-    return 0;
-}

make_planar/make_planar.cpp

@@ -302,11 +302,9 @@ int main(int argc, char* argv[])
 
     std::cout << "Edges removed:" << delEdges->size() << std::endl;
 
-
-    // delete removed edges
     for (edge e: *delEdges) {
         // print removed edges
-        // std::cout << e->adjSource() << std::endl;
+        std::cout << e->adjSource() << std::endl;
         G.delEdge(e);
     }
 

make_planar/ogdf_mps_cactus.cpp

@@ -1,68 +0,0 @@
-#include <ogdf/basic/STNumbering.h>
-#include <ogdf/fileformats/GraphIO.h>
-
-// #include <ogdf/planarity/PlanarSubgraphBoyerMyrvold.h>
-#include <ogdf/planarity/MaximumPlanarSubgraph.h>
-#include <ogdf/planarity/PlanarSubgraphCactus.h>
-#include <ogdf/planarity/MaximalPlanarSubgraphSimple.h>
-
-#include <iostream>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string inputFile = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, inputFile, GraphIO::readGML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-        
-    NodeArray<int> numbering(G);
-    computeSTNumbering(G, numbering, nullptr, nullptr, true);
-    OGDF_ASSERT(num == G.numberOfNodes());
-
-    // print after input
-    // graphPrinter(G);
-    // std::cout << "G Planarity: " << ogdf::isPlanar(G) << std::endl;
-    // std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    // std::cout << "Original number of edges: " << G.numberOfEdges() << std::endl;
-
-    // separator for planarization
-    // <-------------->
-
-    // std::cout << "start planarization" << std::endl;
-    List<edge> *delEdges = new List<edge>; // empty list
-
-    PlanarSubgraphCactus<int> psc;
-    ogdf::MaximalPlanarSubgraphSimple<int> mps(psc);
-    mps.call(G, *delEdges);
-
-    
-    std::cout << delEdges->size() << std::endl;
-
-
-    // delete removed edges
-    //for (edge e: *delEdges) {
-    //    // print removed edges
-    //    // std::cout << e->adjSource() << std::endl;
-    //    G.delEdge(e);
-    //}
-
-
-    // write processed graph to new gml file
-    // GraphIO::write(G, "output.gml", GraphIO::writeGML);
-    
-
-    // std::cout << ogdf::isPlanar(G) << std::endl;
-    // std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    // std::cout << "Subgraph number of edges: " << G.numberOfEdges() << std::endl;
-
-
-    return 0;
-}

make_planar/ogdf_mps_exact.cpp

@@ -1,70 +0,0 @@
-#include <ogdf/basic/STNumbering.h>
-#include <ogdf/fileformats/GraphIO.h>
-// #include <ogdf/basic/extended_graph_alg.h>
-
-#include <ogdf/planarity/PlanarSubgraphFast.h>
-#include <ogdf/planarity/PlanarSubgraphBoyerMyrvold.h>
-#include <ogdf/planarity/PlanarSubgraphPC.h>
-#include <ogdf/planarity/MaximumPlanarSubgraph.h>
-#include <ogdf/planarity/MaximalPlanarSubgraphSimple.h>
-
-#include <iostream>
-#include <map>
-#include <chrono>
-#include <getopt.h>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string inputFile = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, inputFile, GraphIO::readGML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-
-    // print after input
-    // graphPrinter(G);
-    std::cout << "G Planarity: " << ogdf::isPlanar(G) << std::endl;
-    std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    std::cout << "Original number of edges: " << G.numberOfEdges() << std::endl;
-
-    // separator for planarization
-    // <-------------->
-
-    // PQ implementation to make planar subgraph
-    std::cout << "start planarization" << std::endl;
-    List<edge> *delEdges = new List<edge>; // empty list
-
-    std::cout << "running maximum" << std::endl;
-    ogdf::MaximumPlanarSubgraph<int> mps;
-    mps.call(G, *delEdges);
-
-    
-    std::cout << "Edges removed:" << delEdges->size() << std::endl;
-
-
-    // delete removed edges
-    for (edge e: *delEdges) {
-        // print removed edges
-        // std::cout << e->adjSource() << std::endl;
-        G.delEdge(e);
-    }
-
-
-    // write processed graph to new gml file
-    // GraphIO::write(G, "output.gml", GraphIO::writeGML);
-    
-
-    std::cout << "G planarity: " << ogdf::isPlanar(G) << std::endl;
-    std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    std::cout << "Subgraph number of edges: " << G.numberOfEdges() << std::endl;
-
-
-    return 0;
-}

make_planar/ogdf_mps_fast.cpp

@@ -1,74 +0,0 @@
-/* 
- * 
- */
-#include <ogdf/basic/STNumbering.h>
-#include <ogdf/fileformats/GraphIO.h>
-
-#include <ogdf/planarity/PlanarSubgraphFast.h>
-// #include <ogdf/planarity/PlanarSubgraphBoyerMyrvold.h>
-#include <ogdf/planarity/MaximumPlanarSubgraph.h>
-#include <ogdf/planarity/MaximalPlanarSubgraphSimple.h>
-
-#include <iostream>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string inputFile = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, inputFile, GraphIO::readGML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-        
-    NodeArray<int> numbering(G);
-    computeSTNumbering(G, numbering, nullptr, nullptr, true);
-    OGDF_ASSERT(num == G.numberOfNodes());
-
-    // print after input
-    // graphPrinter(G);
-    // std::cout << "G Planarity: " << ogdf::isPlanar(G) << std::endl;
-    // std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    // std::cout << "Original number of edges: " << G.numberOfEdges() << std::endl;
-
-    // separator for planarization
-    // <-------------->
-
-    // PQ implementation to make planar subgraph
-    List<edge> *delEdges = new List<edge>; // empty list
-
-    PlanarSubgraphFast<int> psf;
-    // comment out to use default options
-    // psf.runs(1); 
-    ogdf::MaximalPlanarSubgraphSimple<int> mps(psf);
-    mps.call(G, *delEdges);
-
-    
-	// print edges removed
-    std::cout <<  delEdges->size() << std::endl;
-
-
-    // delete removed edges
-    // for (edge e: *delEdges) {
-    //     // print removed edges
-    //     // std::cout << e->adjSource() << std::endl;
-    //     G.delEdge(e);
-    // }
-
-
-    // write processed graph to new gml file
-    // GraphIO::write(G, "output.gml", GraphIO::writeGML);
-    
-
-    // std::cout << "G planarity: " << ogdf::isPlanar(G) << std::endl;
-    // std::cout << "Original number of nodes: " << G.numberOfNodes() << std::endl;
-    // std::cout << "Subgraph number of edges: " << G.numberOfEdges() << std::endl;
-
-
-    return 0;
-}

make_planar/ogdf_test_planar.cpp

@@ -1,29 +0,0 @@
-/* This code only tests the graph for planarity
- * 
- */
-#include <ogdf/fileformats/GraphIO.h>
-#include <ogdf/basic/extended_graph_alg.h>
-
-#include <iostream>
-
-using namespace ogdf;
-
-
-int main(int argc, char* argv[]) 
-{
-
-    string inputFile = argv[1];
-    Graph G;
-
-    if (!GraphIO::read(G, inputFile, GraphIO::readGML)) {
-        std::cerr << "Could not read input.gml" << std::endl;
-        return 1;
-    }
-
-    // print after input
-    // graphPrinter(G);
-    std::cout << ogdf::isPlanar(G) << std::endl;
-    
-
-    return 0;
-}