diff --git a/scripts/benchmark.sh b/scripts/benchmark.sh
index d9b3e41..f6b40b2 100755
--- a/scripts/benchmark.sh
+++ b/scripts/benchmark.sh
@@ -1,15 +1,18 @@
 #!/bin/bash
 n=$1
+m=$2
 t=0
 all_t=""
 
-TIMEFORMAT=%U
+mkdir -p out/
 printf "%12s\t%12s\n" "seed" "user-time (s)"
+
+TIMEFORMAT=%U
 for i in $(seq 0 9); do
-    t=$( { time bin/hw2.run --gtsp -s $i -n $n > out/gtsp-n${n}-s${i}.log; } 2>&1 )
+    t=$( { time bin/hw2.run --gtsp -s "$i" -n "$n" -m "$m" 2>&1 > tmp/gtsp-m${m}-n${n}-s${i}.log; } 2>&1 )
     all_t="$all_t $t"
     printf "%12d\t%12.3f\n" $i $t
 done
 
 echo
-echo $all_t | scripts/mean.r
+echo "$all_t" | scripts/mean.r
diff --git a/src/branch_and_cut.c b/src/branch_and_cut.c
index 8a3a5cb..142f77e 100644
--- a/src/branch_and_cut.c
+++ b/src/branch_and_cut.c
@@ -85,8 +85,6 @@ static int BNC_solve_node(struct BNC *bnc, int depth)
     int rval = 0;
     double *x = (double *) NULL;
 
-    log_debug("Optimizing...\n");
-
     int is_infeasible;
     rval = LP_optimize(lp, &is_infeasible);
     abort_if(rval, "LP_optimize failed\n");
@@ -104,7 +102,7 @@ static int BNC_solve_node(struct BNC *bnc, int depth)
     if (ceil(objval) > *best_val + LP_EPSILON)
     {
         log_debug("Branch pruned by bound (%.2lf > %.2lf).\n", objval,
-                *best_val);
+                  *best_val);
         rval = 0;
         goto CLEANUP;
     }
@@ -129,7 +127,7 @@ static int BNC_solve_node(struct BNC *bnc, int depth)
         if (ceil(objval) > *best_val + LP_EPSILON)
         {
             log_debug("Branch pruned by bound (%.2lf > %.2lf).\n", objval,
-                    *best_val);
+                      *best_val);
             rval = 0;
             goto CLEANUP;
         }
@@ -153,7 +151,10 @@ static int BNC_solve_node(struct BNC *bnc, int depth)
             log_info("    obj val = %.2lf **\n", objval);
 
             if (bnc->problem_solution_found)
-                bnc->problem_solution_found(bnc->problem_data, bnc->best_x);
+            {
+                rval = bnc->problem_solution_found(bnc->problem_data, bnc->best_x);
+                abort_if(rval, "problem_solution_found failed");
+            }
         }
     }
     else
@@ -178,7 +179,7 @@ static int BNC_branch_node(struct BNC *bnc, double *x, int depth)
     int best_branch_var = BNC_find_best_branching_var(x, num_cols);
 
     log_debug("Branching on variable x%d = %.6lf (depth %d)...\n",
-            best_branch_var, x[best_branch_var], depth);
+              best_branch_var, x[best_branch_var], depth);
 
     log_debug("Fixing variable x%d to one...\n", best_branch_var);
     rval = LP_change_bound(lp, best_branch_var, 'L', 1.0);
@@ -208,11 +209,17 @@ static int BNC_branch_node(struct BNC *bnc, double *x, int depth)
 
 static int BNC_is_integral(double *x, int num_cols)
 {
+#ifdef ALLOW_FRACTIONAL_SOLUTIONS
+    UNUSED(num_cols);
+    UNUSED(x);
+    return 1;
+#else
     for (int i = 0; i < num_cols; i++)
         if (x[i] > LP_EPSILON && x[i] < 1.0 - LP_EPSILON)
             return 0;
 
     return 1;
+#endif
 }
 
 static int BNC_find_best_branching_var(double *x, int num_cols)
diff --git a/src/graph.c b/src/graph.c
index 2ae1f9f..1439606 100644
--- a/src/graph.c
+++ b/src/graph.c
@@ -11,6 +11,8 @@ void graph_init(struct Graph *graph)
     graph->adj = 0;
     graph->node_count = 0;
     graph->edge_count = 0;
+    graph->x_coordinates = 0;
+    graph->y_coordinates = 0;
 }
 
 void graph_free(struct Graph *graph)
@@ -20,6 +22,8 @@ void graph_free(struct Graph *graph)
     if (graph->edges) free(graph->edges);
     if (graph->nodes) free(graph->nodes);
     if (graph->adj) free(graph->adj);
+    if (graph->x_coordinates) free(graph->x_coordinates);
+    if (graph->y_coordinates) free(graph->y_coordinates);
 }
 
 int graph_build(
@@ -86,7 +90,7 @@ int graph_build(
             n = &graph->nodes[b];
             n->adj[n->degree].neighbor_index = a;
             n->adj[n->degree].edge_index = i;
-            n->adj[n->degree].neighbor = &graph->nodes[b];
+            n->adj[n->degree].neighbor = &graph->nodes[a];
             n->adj[n->degree].edge = &graph->edges[i];
             n->degree++;
         }
diff --git a/src/graph.h b/src/graph.h
index 67eed3d..9b00587 100644
--- a/src/graph.h
+++ b/src/graph.h
@@ -41,6 +41,9 @@ struct Graph
     struct Edge *edges;
     struct Node *nodes;
 
+    double *x_coordinates;
+    double *y_coordinates;
+
     struct Adjacency *adj;
 };
 
diff --git a/src/gtsp-comb.c b/src/gtsp-comb.c
new file mode 100644
index 0000000..07855b8
--- /dev/null
+++ b/src/gtsp-comb.c
@@ -0,0 +1,473 @@
+#include <assert.h>
+#include "gtsp.h"
+#include "util.h"
+
+int add_comb_cut(
+        struct LP *lp,
+        struct Graph *graph,
+        int current_component,
+        int *clusters,
+        int *components,
+        int *component_sizes,
+        int *teeth,
+        int tooth_count,
+        double *x)
+{
+    int rval = 0;
+
+    char sense = 'G';
+
+    const int node_count = graph->node_count;
+    const int edge_count = graph->edge_count;
+
+    struct Row *cut = 0;
+    int *rmatind = 0;
+    double *rmatval = 0;
+
+    rmatind = (int *) malloc((node_count + edge_count) * sizeof(int));
+    rmatval = (double *) malloc((node_count + edge_count) * sizeof(double));
+    abort_if(!rmatind, "could not allocate rmatind");
+    abort_if(!rmatval, "could not allocate rmatval");
+
+    double rhs = -component_sizes[current_component] - tooth_count +
+                 (tooth_count + 1) / 2;
+
+    int nz = 0;
+
+    // Edges inside handle
+    for (int i = 0; i < edge_count; i++)
+    {
+        struct Edge *e = &graph->edges[i];
+        if (components[clusters[e->from->index]] != current_component) continue;
+        if (components[clusters[e->to->index]] != current_component) continue;
+
+        rmatind[nz] = node_count + e->index;
+        rmatval[nz] = -1.0;
+        nz++;
+
+        log_verbose("  handle (%d %d)\n", e->from->index, e->to->index);
+    }
+
+    // Edges inside each tooth
+    for (int i = 0; i < edge_count; i++)
+    {
+        struct Edge *e = &graph->edges[i];
+        struct Node *from = e->from;
+        struct Node *to = e->to;
+
+        if (teeth[clusters[from->index]] < 0) continue;
+        if (teeth[clusters[to->index]] < 0) continue;
+        if (teeth[clusters[from->index]] != teeth[clusters[to->index]])
+            continue;
+
+        log_verbose("  tooth (%d %d)\n", e->from->index, e->to->index);
+
+        rmatind[nz] = node_count + e->index;
+        rmatval[nz] = -1.0;
+        nz++;
+    }
+
+    // Lifting of the nodes
+    for (int i = 0; i < node_count; i++)
+    {
+        double val;
+        struct Node *n = &graph->nodes[i];
+        int c = clusters[n->index];
+
+        if (components[c] == current_component)
+            val = (teeth[c] < 0 ? 1.0 : 2.0);
+        else
+            val = (teeth[c] < 0 ? 0.0 : 1.0);
+
+        if (val == 0.0) continue;
+
+        rmatind[nz] = n->index;
+        rmatval[nz] = val;
+        nz++;
+
+        rhs += val;
+    }
+
+    log_verbose("Generated cut:\n");
+    for (int i = 0; i < nz; i++)
+            log_verbose("    %.2lf x%d (%.4lf)\n", rmatval[i], rmatind[i],
+                        x[rmatind[i]]);
+    log_verbose("    %c %.2lf\n", sense, rhs);
+
+    if (OPTIMAL_X)
+    {
+        double sum = 0;
+        for (int i = 0; i < nz; i++)
+            sum += rmatval[i] * OPTIMAL_X[rmatind[i]];
+        abort_if(sum <= rhs - LP_EPSILON, "cannot add invalid cut");
+    }
+
+    double lhs = 0.0;
+    for (int i = 0; i < nz; i++)
+        lhs += rmatval[i] * x[rmatind[i]];
+
+    log_verbose("Violation: %.4lf >= %.4lf\n", lhs, rhs);
+
+    if (lhs + LP_EPSILON > rhs) goto CLEANUP;
+
+    cut = (struct Row *) malloc(sizeof(struct Row));
+    abort_if(!cut, "could not allocate cut");
+
+    cut->nz = nz;
+    cut->sense = sense;
+    cut->rhs = rhs;
+    cut->rmatval = rmatval;
+    cut->rmatind = rmatind;
+
+    rval = LP_add_cut(lp, cut);
+    abort_if(rval, "LP_add_cut failed");
+
+    CLEANUP:
+    if (rmatind) free(rmatind);
+    if (rmatval) free(rmatval);
+    return rval;
+}
+
+int find_components(
+        struct Graph *graph, double *x, int *components, int *component_sizes)
+{
+    int rval = 0;
+    struct Node **stack = 0;
+
+    const int node_count = graph->node_count;
+
+    for (int i = 0; i < node_count; i++)
+    {
+        components[i] = -1;
+        graph->nodes[i].mark = 0;
+    }
+
+    int stack_top = 0;
+    stack = (struct Node **) malloc(node_count * sizeof(struct Node *));
+    abort_if(!stack, "could not allocate stack");
+
+    for (int i = 0; i < node_count; i++)
+    {
+        struct Node *root = &graph->nodes[i];
+        if (root->mark) continue;
+
+        stack[stack_top++] = root;
+
+        while (stack_top > 0)
+        {
+            struct Node *n = stack[--stack_top];
+            components[n->index] = i;
+
+            for (int j = 0; j < n->degree; j++)
+            {
+                struct Adjacency *adj = &n->adj[j];
+                struct Node *neighbor = adj->neighbor;
+
+                if (neighbor->mark) continue;
+
+                double x_e = x[adj->edge->index];
+                if (x_e < LP_EPSILON) continue;
+                if (x_e > 1 - LP_EPSILON) continue;
+
+                stack[stack_top++] = neighbor;
+                neighbor->mark = 1;
+            }
+        }
+    }
+
+    for (int i = 0; i < node_count; i++)
+        component_sizes[i] = 0;
+
+    for (int i = 0; i < node_count; i++)
+        component_sizes[components[i]]++;
+
+    log_verbose("Components:\n");
+    for (int i = 0; i < graph->node_count; i++)
+            log_verbose("    %d %d\n", i, components[i]);
+
+    log_verbose("Component sizes:\n");
+    for (int i = 0; i < graph->node_count; i++)
+            log_verbose("    %d %d\n", i, component_sizes[i]);
+
+    CLEANUP:
+    if (stack) free(stack);
+    return rval;
+}
+
+int find_teeth(
+        struct Graph *graph,
+        double *x,
+        int current_component,
+        int *components,
+        int *teeth,
+        int *tooth_count)
+{
+    const int node_count = graph->node_count;
+    const int edge_count = graph->edge_count;
+
+    for (int i = 0; i < node_count; i++)
+    {
+        graph->nodes[i].mark = 0;
+        teeth[i] = -1;
+    }
+
+    *tooth_count = 0;
+
+    for (int i = 0; i < edge_count; i++)
+    {
+        struct Edge *e = &graph->edges[i];
+        struct Node *from = e->from;
+        struct Node *to = e->to;
+
+        if (x[e->index] < 1 - LP_EPSILON) continue;
+
+        if (to->mark || from->mark) continue;
+
+        int z = 0;
+        if (components[from->index] == current_component) z++;
+        if (components[to->index] == current_component) z++;
+        if (z != 1) continue;
+
+        to->mark = 1;
+        from->mark = 1;
+
+        teeth[to->index] = *tooth_count;
+        teeth[from->index] = *tooth_count;
+
+        (*tooth_count)++;
+    }
+
+    return 0;
+}
+
+int write_shrunken_graph(
+        double *shrunken_x,
+        struct Graph *shrunken_graph,
+        int const cluster_count);
+
+static int shrink_clusters(
+        const struct GTSP *data,
+        double *x,
+        struct Graph *shrunken_graph,
+        double *shrunken_x)
+{
+    int rval = 0;
+
+    double *x_coords = 0;
+    double *y_coords = 0;
+    int *cluster_sizes = 0;
+
+    const int *clusters = data->clusters;
+    const int cluster_count = data->cluster_count;
+    const struct Graph *graph = data->graph;
+
+    int *edges = 0;
+    int *edge_map = 0;
+    int edge_count = (cluster_count * (cluster_count - 1)) / 2;
+
+    edge_map = (int *) malloc(cluster_count * cluster_count * sizeof(int));
+    abort_if(!edge_map, "could not allocate edge_map");
+
+    edges = (int *) malloc(2 * edge_count * sizeof(int));
+    abort_if(!edges, "could not allocate edges");
+
+    cluster_sizes = (int *) malloc(cluster_count * sizeof(int));
+    x_coords = (double *) malloc(cluster_count * sizeof(double));
+    y_coords = (double *) malloc(cluster_count * sizeof(double));
+
+    abort_if(!cluster_sizes, "could not allocate cluster_sizes");
+    abort_if(!x_coords, "could not allocate x_coords");
+    abort_if(!y_coords, "could not allocate y_coords");
+
+    for (int i = 0; i < cluster_count; i++)
+    {
+        x_coords[i] = 0.0;
+        y_coords[i] = 0.0;
+        cluster_sizes[i] = 0;
+    }
+
+    for (int i = 0; i < graph->node_count; i++)
+    {
+        struct Node *n = &graph->nodes[i];
+        int c = clusters[n->index];
+
+        cluster_sizes[c]++;
+        x_coords[c] += graph->x_coordinates[n->index];
+        y_coords[c] += graph->y_coordinates[n->index];
+    }
+
+    for (int i = 0; i < cluster_count; i++)
+    {
+        x_coords[i] = x_coords[i] / cluster_sizes[i];
+        y_coords[i] = y_coords[i] / cluster_sizes[i];
+    }
+
+    shrunken_graph->x_coordinates = x_coords;
+    shrunken_graph->y_coordinates = y_coords;
+
+    int curr_edge = 0;
+    for (int i = 0; i < cluster_count; i++)
+    {
+        for (int j = i + 1; j < cluster_count; j++)
+        {
+            edges[curr_edge * 2] = i;
+            edges[curr_edge * 2 + 1] = j;
+            edge_map[i * cluster_count + j] = curr_edge;
+            edge_map[j * cluster_count + i] = curr_edge;
+            curr_edge++;
+        }
+    }
+
+    assert(curr_edge == edge_count);
+
+    rval = graph_build(cluster_count, edge_count, edges, 0, shrunken_graph);
+    abort_if(rval, "graph_build failed");
+
+    for (int i = 0; i < edge_count; i++)
+        shrunken_x[i] = 0.0;
+
+    for (int i = 0; i < graph->edge_count; i++)
+    {
+        struct Edge *e = &graph->edges[i];
+
+        int from = clusters[e->from->index];
+        int to = clusters[e->to->index];
+        int shunk_e_index = edge_map[from * cluster_count + to];
+
+        shrunken_x[shunk_e_index] += x[graph->node_count + e->index];
+    }
+
+    CLEANUP:
+    if (edges) free(edges);
+    if (edge_map) free(edge_map);
+    if (cluster_sizes) free(cluster_sizes);
+    return rval;
+}
+
+int find_comb_cuts(struct LP *lp, struct GTSP *data)
+{
+    int rval = 0;
+
+    double *x = 0;
+    double *shrunken_x = 0;
+
+    int *teeth = 0;
+    int *components = 0;
+    int *component_sizes = 0;
+
+    int num_cols = LP_get_num_cols(lp);
+    x = (double *) malloc(num_cols * sizeof(double));
+    abort_if(!x, "could not allocate x");
+
+    rval = LP_get_x(lp, x);
+    abort_if(rval, "LP_get_x failed");
+
+    struct Graph shrunken_graph;
+    graph_init(&shrunken_graph);
+
+    const int cluster_count = data->cluster_count;
+    const int shrunken_edge_count = (cluster_count * (cluster_count - 1)) / 2;
+
+    shrunken_x = (double *) malloc(shrunken_edge_count * sizeof(double));
+    abort_if(!shrunken_x, "could not allocate shrunken_x");
+
+    rval = shrink_clusters(data, x, &shrunken_graph, shrunken_x);
+    abort_if(rval, "shrink_clusters failed");
+
+    rval = write_shrunken_graph(shrunken_x, &shrunken_graph, cluster_count);
+    abort_if(rval, "write_shrunken_graph failed");
+
+    teeth = (int *) malloc(cluster_count * sizeof(int));
+    components = (int *) malloc(cluster_count * sizeof(int));
+    component_sizes = (int *) malloc(cluster_count * sizeof(int));
+
+    abort_if(!teeth, "could not allocate teeth");
+    abort_if(!components, "could not allocate components");
+    abort_if(!component_sizes, "could not allocate component_sizes");
+
+    rval = find_components(&shrunken_graph, shrunken_x, components,
+                           component_sizes);
+    abort_if(rval, "find_components failed");
+
+    #if LOG_LEVEL >= LOG_LEVEL_DEBUG
+    int original_cut_pool_size = lp->cut_pool_size;
+    #endif
+
+    for (int i = 0; i < cluster_count; i++)
+    {
+        if (component_sizes[i] < 3) continue;
+
+        int tooth_count;
+        rval = find_teeth(&shrunken_graph, shrunken_x, i, components, teeth,
+                          &tooth_count);
+        abort_if(rval, "find_teeth failed");
+
+        log_verbose("Component %d has %d teeth:\n", i, tooth_count);
+        for (int j = 0; j < cluster_count; j++)
+        {
+            if (teeth[j] < 0) continue;
+            log_verbose("    %d %d\n", j, teeth[j]);
+        }
+
+        if (tooth_count % 2 == 0) continue;
+
+        rval = add_comb_cut(lp, data->graph, i, data->clusters, components,
+                            component_sizes, teeth, tooth_count, x);
+        abort_if(rval, "add_comb_cut failed");
+    }
+
+    log_debug("    %d combs\n", lp->cut_pool_size - original_cut_pool_size);
+
+    CLEANUP:
+    graph_free(&shrunken_graph);
+    if (teeth) free(teeth);
+    if (components) free(components);
+    if (component_sizes) free(component_sizes);
+    if (shrunken_x) free(shrunken_x);
+    return rval;
+}
+
+int write_shrunken_graph(
+        double *shrunken_x,
+        struct Graph *shrunken_graph,
+        int const cluster_count)
+{
+    int rval = 0;
+
+    FILE *file = 0;
+
+    file = fopen("gtsp-shrunken.in", "w");
+    abort_if(!file, "could not open file");
+
+    fprintf(file, "%d %d\n", (*shrunken_graph).node_count, cluster_count);
+    for (int i = 0; i < (*shrunken_graph).node_count; i++)
+    {
+        fprintf(file, "%.2lf %.2lf %d\n", (*shrunken_graph).x_coordinates[i],
+                (*shrunken_graph).y_coordinates[i], i);
+    }
+
+    fclose(file);
+
+    file = fopen("gtsp-shrunken.out", "w");
+    abort_if(!file, "could not open file");
+
+    int positive_edge_count = 0;
+    for (int i = 0; i < (*shrunken_graph).edge_count; i++)
+        if (shrunken_x[i] > LP_EPSILON)
+            positive_edge_count++;
+
+    fprintf(file, "%d %d\n", (*shrunken_graph).node_count,
+            (*shrunken_graph).edge_count);
+
+    fprintf(file, "%d\n", positive_edge_count);
+
+    for (int i = 0; i < (*shrunken_graph).edge_count; i++)
+        if (shrunken_x[i] > LP_EPSILON)
+            fprintf(file, "%d %d %.4lf\n",
+                    (*shrunken_graph).edges[i].from->index,
+                    (*shrunken_graph).edges[i].to->index, shrunken_x[i]);
+    fclose(file);
+
+    CLEANUP:
+    return rval;
+}
\ No newline at end of file
diff --git a/src/gtsp-comb.h b/src/gtsp-comb.h
new file mode 100644
index 0000000..ee600e8
--- /dev/null
+++ b/src/gtsp-comb.h
@@ -0,0 +1,6 @@
+#ifndef PROJECT_GTSP_COMB_H
+#define PROJECT_GTSP_COMB_H
+
+int find_comb_cuts(struct LP *lp, struct GTSP *data);
+
+#endif //PROJECT_GTSP_COMB_H
diff --git a/src/gtsp-subtour.c b/src/gtsp-subtour.c
index fa9d1ea..13df7b6 100644
--- a/src/gtsp-subtour.c
+++ b/src/gtsp-subtour.c
@@ -143,7 +143,7 @@ int static add_subtour_cut(
 
     log_verbose("Generated cut:\n");
     for (int i = 0; i < newnz; i++)
-            log_verbose("%8.2f x%d\n", rmatval[i], rmatind[i]);
+            log_verbose("    %8.2f x%d\n", rmatval[i], rmatind[i]);
     log_verbose("    %c %.2lf\n", sense, rhs);
 
     if (OPTIMAL_X)
@@ -213,12 +213,9 @@ int find_exact_subtour_cuts(
     abort_if(rval, "find_exact_subtour_cuts_cluster_to_cluster failed");
 
     added_cuts_count = lp->cut_pool_size - original_cut_pool_size;
+    log_debug("    %d cluster-to-cluster\n", added_cuts_count);
     if (added_cuts_count > 0)
-    {
-        log_debug("Added %d cluster-to-cluster subtour cuts\n",
-                added_cuts_count);
         goto CLEANUP;
-    }
 
     // Constraints (2.2)
     original_cut_pool_size = lp->cut_pool_size;
@@ -227,11 +224,9 @@ int find_exact_subtour_cuts(
     abort_if(rval, "find_exact_subtour_cuts_node_to_cluster failed");
 
     added_cuts_count = lp->cut_pool_size - original_cut_pool_size;
+    log_debug("    %d node-to-cluster\n", added_cuts_count);
     if (added_cuts_count > 0)
-    {
-        log_debug("Added %d node-to-cluster subtour cuts\n", added_cuts_count);
         goto CLEANUP;
-    }
 
     // Constraints (2.3)
     original_cut_pool_size = lp->cut_pool_size;
@@ -240,11 +235,9 @@ int find_exact_subtour_cuts(
     abort_if(rval, "find_exact_subtour_cuts_node_to_node failed");
 
     added_cuts_count = lp->cut_pool_size - original_cut_pool_size;
+    log_debug("    %d node-to-node\n", added_cuts_count);
     if (added_cuts_count > 0)
-    {
-        log_debug("Added %d node-to-node subtour cuts\n", added_cuts_count);
         goto CLEANUP;
-    }
 
     CLEANUP:
     graph_free(&digraph);
diff --git a/src/gtsp.c b/src/gtsp.c
index 11fdeb8..5a09bf7 100644
--- a/src/gtsp.c
+++ b/src/gtsp.c
@@ -2,36 +2,22 @@
 #include <stdlib.h>
 #include <float.h>
 #include <getopt.h>
+#include <math.h>
 #include "gtsp.h"
 #include "geometry.h"
 #include "util.h"
 #include "flow.h"
 #include "branch_and_cut.h"
-#include "math.h"
 #include "gtsp-subtour.h"
 
 double *OPTIMAL_X = 0;
 
-static int get_edge_num(int node_count, int from, int to)
-{
-    int idx = node_count;
-
-    for (int k = 0; k < from; k++)
-        idx += node_count - k - 1;
-
-    idx += to - from - 1;
-
-    return idx;
-}
-
 int GTSP_init_data(struct GTSP *data)
 {
     int rval = 0;
 
     data->clusters = 0;
     data->cluster_count = 0;
-    data->x_coordinates = 0;
-    data->y_coordinates = 0;
 
     data->graph = (struct Graph *) malloc(sizeof(struct Graph));
     abort_if(!data->graph, "could not allocate data->graph");
@@ -52,8 +38,6 @@ void GTSP_free(struct GTSP *data)
     free(data->graph);
 
     if (data->clusters) free(data->clusters);
-    if (data->x_coordinates) free(data->x_coordinates);
-    if (data->y_coordinates) free(data->y_coordinates);
 }
 
 int GTSP_create_random_problem(
@@ -156,11 +140,17 @@ abort_if(!data->graph, "could not allocate data->graph");
     data->graph = graph;
     data->clusters = clusters;
     data->cluster_count = cluster_count;
+<<<<<<< HEAD
     data->x_coordinates = x_coords;
     data->y_coordinates = y_coords;
 	data->dist_matrix = dist_matrix;
 	data->vertex_set = cluster_member;
 		
+=======
+    graph->x_coordinates = x_coords;
+    graph->y_coordinates = y_coords;
+
+>>>>>>> 550b5f1912da4f50cd0bd0a7d2f19cdbf695b180
     CLEANUP:
     if (weights) free(weights);
     if (edges) free(edges);
@@ -226,43 +216,47 @@ int GTSP_init_lp(struct LP *lp, struct GTSP *data)
 int GTSP_add_cutting_planes(struct LP *lp, struct GTSP *data)
 {
     int rval = 0;
-
-    int round = 0;
-
-    int violation_total = 3;
-    int violation_current = 0;
-    double violations[] = {1.0, 0.1, LP_EPSILON};
+    int current_round = 0;
 
     while (1)
     {
-        round++;
+        if (current_round > 0)
+        {
+            int is_infeasible;
+            rval = LP_optimize(lp, &is_infeasible);
+            abort_if(rval, "LP_optimize failed");
+
+            if (is_infeasible) break;
+        }
+
+        current_round++;
 
-        log_debug("Finding subtour cuts, round %d, violation %.4lf...\n", round,
-                violations[violation_current]);
+        int original_cut_pool_size;
+        int added_cuts_count;
 
-        int original_cut_pool_size = lp->cut_pool_size;
-        rval = find_exact_subtour_cuts(lp, data, violations[violation_current]);
+        original_cut_pool_size = lp->cut_pool_size;
+        log_debug("Finding subtour cuts, round %d...\n", current_round);
+
+        rval = find_exact_subtour_cuts(lp, data, LP_EPSILON);
         abort_if(rval, "find_exact_subtour_cuts failed");
 
-        if (lp->cut_pool_size - original_cut_pool_size == 0)
-        {
-            if (++violation_current < violation_total)
-            {
-                log_debug("No cuts found. Decreasing minimum cut violation.\n");
-                continue;
-            }
-            else
-            {
-                log_debug("No additional cuts found.\n");
-                break;
-            }
-        }
+        added_cuts_count = lp->cut_pool_size - original_cut_pool_size;
+        if (added_cuts_count > 0)
+            continue;
+
+#ifdef ENABLE_COMB_INEQUALITIES
+        original_cut_pool_size = lp->cut_pool_size;
+        log_debug("Finding comb cuts, round %d...\n", current_round);
+
+        rval = find_comb_cuts(lp, data);
+        abort_if(rval, "find_comb_cuts failed");
 
-        int is_infeasible;
-        rval = LP_optimize(lp, &is_infeasible);
-        abort_if(rval, "LP_optimize failed");
+        added_cuts_count = lp->cut_pool_size - original_cut_pool_size;
+        if (added_cuts_count > 0)
+            continue;
+#endif
 
-        if (is_infeasible) break;
+        break;
     }
 
     CLEANUP:
@@ -278,12 +272,14 @@ int GTSP_write_problem(struct GTSP *data, char *filename)
     file = fopen(filename, "w");
     abort_if(!file, "could not open file");
 
-    fprintf(file, "%d %d\n", data->graph->node_count, data->cluster_count);
+    const struct Graph *graph = data->graph;
 
-    for (int i = 0; i < data->graph->node_count; i++)
+    fprintf(file, "%d %d\n", graph->node_count, data->cluster_count);
+
+    for (int i = 0; i < graph->node_count; i++)
     {
-        fprintf(file, "%.2lf %.2lf %d\n", data->x_coordinates[i],
-                data->y_coordinates[i], data->clusters[i]);
+        fprintf(file, "%.2lf %.2lf %d\n", graph->x_coordinates[i],
+                graph->y_coordinates[i], data->clusters[i]);
     }
 
     CLEANUP:
@@ -322,12 +318,13 @@ int GTSP_write_solution(struct GTSP *data, char *filename, double *x)
     return rval;
 }
 
-int GTSP_read_solution(char *filename, double **p_x)
+int GTSP_read_solution(struct GTSP *gtsp, char *filename, double **p_x)
 {
     int rval = 0;
 
     int node_count;
     int edge_count;
+    int *edge_map = 0;
 
     double *x;
 
@@ -351,31 +348,138 @@ int GTSP_read_solution(char *filename, double **p_x)
     rval = fscanf(file, "%d", &edge_count);
     abort_if(rval != 1, "invalid input format (positive edge count)");
 
+    edge_map = (int *) malloc(node_count * node_count * sizeof(int));
+    abort_if(!edge_map, "could not allocate edge_map");
+
+    int k = node_count;
+    for (int i = 0; i < node_count; i++)
+    {
+        for (int j = i + 1; j < node_count; j++)
+        {
+            if (gtsp->clusters[i] == gtsp->clusters[j]) continue;
+            edge_map[i * node_count + j] = k;
+            edge_map[j * node_count + i] = k;
+            k++;
+        }
+    }
+
     for (int i = 0; i < edge_count; i++)
     {
         int from, to, edge;
-        rval = fscanf(file, "%d %d", &from, &to);
-        abort_if(rval != 2, "invalid input format (edge endpoints)");
+        double val;
+        rval = fscanf(file, "%d %d %lf", &from, &to, &val);
+        abort_if(rval != 3, "invalid input format (edge endpoints)");
 
-        if (from > to) swap(from, to);
-
-        edge = get_edge_num(node_count, from, to);
+        edge = edge_map[from * node_count + to];
         abort_if(edge > num_cols, "invalid edge");
 
-        x[from] += 0.5;
-        x[to] += 0.5;
-        x[edge] = 1;
+        x[from] += val / 2;
+        x[to] += val / 2;
+        x[edge] = val;
     }
 
     for (int i = 0; i < num_cols; i++)
     {
         if (x[i] <= LP_EPSILON) continue;
-        log_debug(" x%-3d = %.2f\n", i, x[i]);
+        log_debug("    x%-5d = %.6f\n", i, x[i]);
     }
 
     *p_x = x;
     rval = 0;
 
+    CLEANUP:
+    if (edge_map) free(edge_map);
+    return rval;
+}
+
+int GTSP_check_solution(struct GTSP *data, double *x)
+{
+    int rval = 0;
+    int *cluster_mark = 0;
+
+    struct Node **stack = 0;
+    int stack_top = 0;
+
+    struct Graph *graph = data->graph;
+    const int node_count = graph->node_count;
+    const int edge_count = graph->edge_count;
+
+    cluster_mark = (int *) malloc(data->cluster_count * sizeof(int));
+    abort_if(!cluster_mark, "could not allocate cluster_mark");
+
+    stack = (struct Node **) malloc(graph->node_count * sizeof(struct Node *));
+    abort_if(!stack, "could not allocate stack");
+
+    for (int i = 0; i < node_count + edge_count; i++)
+    {
+        abort_iff(x[i] < 1.0 - LP_EPSILON && x[i] > LP_EPSILON,
+                "solution is not integral: x%d = %.4lf", i, x[i]);
+
+        abort_iff(x[i] > 1.0 + LP_EPSILON || x[i] < 0.0 - LP_EPSILON,
+                "value out of bounds: x%d = %.4lf", i, x[i]);
+    }
+
+    for (int i = 0; i < node_count; i++)
+        graph->nodes[i].mark = 0;
+
+    for (int i = 0; i < data->cluster_count; i++)
+        cluster_mark[i] = 0;
+
+    int initial;
+    for (initial = 0; initial < node_count; initial++)
+        if (x[initial] > 1.0 - LP_EPSILON) break;
+
+    abort_if(initial == node_count, "no initial node");
+
+    stack[stack_top++] = &graph->nodes[initial];
+    graph->nodes[initial].mark = 1;
+
+    while (stack_top > 0)
+    {
+        struct Node *n = stack[--stack_top];
+        cluster_mark[data->clusters[n->index]]++;
+
+        for (int i = 0; i < n->degree; i++)
+        {
+            struct Adjacency *adj = &n->adj[i];
+            struct Node *neighbor = adj->neighbor;
+
+            if (neighbor->mark) continue;
+            if (x[node_count + adj->edge->index] < LP_EPSILON) continue;
+
+            stack[stack_top++] = neighbor;
+            neighbor->mark = 1;
+        }
+    }
+
+    for (int i = 0; i < data->cluster_count; i++)
+        abort_if(cluster_mark[i] != 1, "cluster not visited exactly one time");
+
+    log_info("    solution is valid\n");
+
+    CLEANUP:
+    if (stack) free(stack);
+    if (cluster_mark) free(cluster_mark);
+    return rval;
+}
+
+int GTSP_solution_found(struct GTSP *data, double *x)
+{
+    int rval = 0;
+
+    char filename[100];
+
+    sprintf(filename, "tmp/gtsp-m%d-n%d-s%d.out", data->cluster_count,
+            data->graph->node_count, SEED);
+
+    log_info("Writting solution to file %s\n", filename);
+    rval = GTSP_write_solution(data, filename, x);
+    abort_if(rval, "GTSP_write_solution failed");
+
+    log_info("Checking solution...\n");
+    rval = GTSP_check_solution(data, x);
+    abort_if(rval, "GTSP_check_solution failed");
+
     CLEANUP:
     return rval;
 }
@@ -387,11 +491,12 @@ static const struct option options_tab[] = {{"help", no_argument, 0, 'h'},
         {"optimal", required_argument, 0, 'x'},
         {"seed", required_argument, 0, 's'},
         {(char *) 0, (int) 0, (int *) 0, (int) 0}};
-
 static int input_node_count = -1;
 static int input_cluster_count = -1;
 static int grid_size = 100;
 
+static char input_x_filename[1000] = {0};
+
 static void GTSP_print_usage()
 {
     printf("Parameters:\n");
@@ -433,8 +538,7 @@ static int GTSP_parse_args(int argc, char **argv)
                 break;
 
             case 'x':
-                rval = GTSP_read_solution(optarg, &OPTIMAL_X);
-                abort_if(rval, "GTSP_read_solution failed");
+                strcpy(input_x_filename, optarg);
                 break;
 
             case 's':
@@ -443,12 +547,14 @@ static int GTSP_parse_args(int argc, char **argv)
 
             case ':':
                 fprintf(stderr, "option '-%c' requires an argument\n", optopt);
-                return 1;
+                rval = 1;
+                goto CLEANUP;
 
             case '?':
             default:
                 fprintf(stderr, "option '-%c' is invalid\n", optopt);
-                return 1;
+                rval = 1;
+                goto CLEANUP;
 
         }
     }
@@ -481,18 +587,6 @@ static int GTSP_parse_args(int argc, char **argv)
     return rval;
 }
 
-int GTSP_solution_found(struct GTSP *data, double *x)
-{
-    int rval = 0;
-
-    log_info("Writting integral solution to file gtsp.out\n");
-    rval = GTSP_write_solution(data, "gtsp.out", x);
-    abort_if(rval, "GTSP_write_solution failed");
-
-    CLEANUP:
-    return rval;
-}
-
 double FLOW_CPU_TIME = 0;
 double LP_SOLVE_TIME = 0;
 double LP_CUT_POOL_TIME = 0;
@@ -527,11 +621,20 @@ int GTSP_main(int argc, char **argv)
     rval = GTSP_create_random_problem(input_node_count, input_cluster_count,
             grid_size, &data);
     abort_if(rval, "GTSP_create_random_problem failed");
+<<<<<<< HEAD
 	int init_val ;
 	
 	init_val = inital_tour_value(&data);
     log_info("Writing random instance to file gtsp.in\n");
     rval = GTSP_write_problem(&data, "gtsp.in");
+=======
+
+    char filename[100];
+    sprintf(filename, "input/gtsp-m%d-n%d-s%d.in", input_cluster_count,
+            input_node_count, SEED);
+    log_info("Writing random instance to file %s\n", filename);
+    rval = GTSP_write_problem(&data, filename);
+>>>>>>> 550b5f1912da4f50cd0bd0a7d2f19cdbf695b180
     abort_if(rval, "GTSP_write_problem failed");
 
     bnc.best_obj_val = init_val;
@@ -542,11 +645,28 @@ int GTSP_main(int argc, char **argv)
     bnc.problem_solution_found = (int (*)(
             void *, double *)) GTSP_solution_found;
 
-    if (OPTIMAL_X)
+    double opt_val = 0.0;
+
+    if (strlen(input_x_filename) == 0)
+    {
+        sprintf(input_x_filename, "optimal/gtsp-m%d-n%d-s%d.out",
+                input_cluster_count, input_node_count, SEED);
+
+        FILE *file = fopen(input_x_filename, "r");
+
+        if (!file)
+            input_x_filename[0] = 0;
+        else
+            fclose(file);
+    }
+
+    if (strlen(input_x_filename) > 0)
     {
+        rval = GTSP_read_solution(&data, input_x_filename, &OPTIMAL_X);
+        abort_if(rval, "GTSP_read_solution failed");
+
         log_info("Optimal solution is available. Cuts will be checked.\n");
 
-        double opt_val = 0.0;
         for (int i = 0; i < data.graph->edge_count; i++)
         {
             struct Edge *e = &data.graph->edges[i];
@@ -560,9 +680,9 @@ int GTSP_main(int argc, char **argv)
     rval = BNC_init_lp(&bnc);
     abort_if(rval, "BNC_init_lp failed");
 
-    log_info("Writing LP to file gtsp.lp...\n");
-    rval = LP_write(bnc.lp, "gtsp.lp");
-    abort_if(rval, "LP_write failed");
+//    log_info("Writing LP to file gtsp.lp...\n");
+//    rval = LP_write(bnc.lp, "gtsp.lp");
+//    abort_if(rval, "LP_write failed");
 
     log_info("Starting branch-and-cut solver...\n");
     rval = BNC_solve(&bnc);
@@ -573,6 +693,13 @@ int GTSP_main(int argc, char **argv)
     log_info("Optimal integral solution:\n");
     log_info("    obj value = %.2lf **\n", bnc.best_obj_val);
 
+    if (OPTIMAL_X)
+    {
+        abort_iff(bnc.best_obj_val > opt_val,
+                "Solution is not optimal: %.4lf > %.4lf", bnc.best_obj_val,
+                opt_val);
+    }
+
     log_info("Branch-and-bound nodes: %d\n", BNC_NODE_COUNT);
     log_info("Max-flow calls: %d\n", FLOW_MAX_FLOW_COUNT);
     log_info("Max-flow computation time: %.2lf\n", FLOW_CPU_TIME);
diff --git a/src/gtsp.h b/src/gtsp.h
index 86f1729..9292095 100644
--- a/src/gtsp.h
+++ b/src/gtsp.h
@@ -1,7 +1,3 @@
-//
-// Created by isoron on 18/03/15.
-//
-
 #ifndef _PROJECT_GTSP_H_
 #define _PROJECT_GTSP_H_
 
@@ -21,11 +17,14 @@ struct GTSP
 
     int *clusters;
     int cluster_count;
+<<<<<<< HEAD
 
     double *x_coordinates;
     double *y_coordinates;
     int** dist_matrix;
     struct CLUSTER *vertex_set;
+=======
+>>>>>>> 550b5f1912da4f50cd0bd0a7d2f19cdbf695b180
 };
 
 int GTSP_create_random_problem(
diff --git a/src/lp.c b/src/lp.c
index f2cd0dd..67382f9 100644
--- a/src/lp.c
+++ b/src/lp.c
@@ -165,10 +165,11 @@ int LP_optimize(struct LP *lp, int *infeasible)
 
     *infeasible = 0;
 
+#if LOG_LEVEL >= LOG_LEVEL_DEBUG
     int numrows = CPXgetnumrows(lp->cplex_env, lp->cplex_lp);
     int numcols = CPXgetnumcols(lp->cplex_env, lp->cplex_lp);
-
     log_debug("Optimizing LP (%d rows %d cols)...\n", numrows, numcols);
+#endif
 
     double time_before = get_current_time();
     rval = CPXdualopt(lp->cplex_env, lp->cplex_lp);
@@ -228,7 +229,7 @@ int LP_remove_old_cuts(struct LP *lp)
 
     log_verbose("Old cplex row index:\n");
     for (int i = 0; i < lp->cut_pool_size; i++)
-        log_verbose("    %d\n", lp->cut_pool[i]->cplex_row_index);
+            log_verbose("    %d\n", lp->cut_pool[i]->cplex_row_index);
 
     log_verbose("Should remove:\n");
     for (int i = 0; i < lp->cut_pool_size; i++)
@@ -250,7 +251,7 @@ int LP_remove_old_cuts(struct LP *lp)
         {
             struct Row *cut = lp->cut_pool[j];
 
-            if (cut->cplex_row_index == i - count) cut->cplex_row_index = 0;
+            if (cut->cplex_row_index == i - count) cut->cplex_row_index = -1;
             else if (cut->cplex_row_index > i - count) cut->cplex_row_index--;
         }
 
@@ -259,7 +260,7 @@ int LP_remove_old_cuts(struct LP *lp)
 
     log_verbose("New cplex row index:\n");
     for (int i = 0; i < lp->cut_pool_size; i++)
-        log_verbose("    %d\n", lp->cut_pool[i]->cplex_row_index);
+            log_verbose("    %d\n", lp->cut_pool[i]->cplex_row_index);
 
     int start = 0;
     int end = -1;
@@ -298,7 +299,7 @@ int LP_remove_old_cuts(struct LP *lp)
 
     if (count > 0)
     {
-        log_info("Found and removed %d old cuts\n", count);
+        log_debug("Found and removed %d old cuts\n", count);
         rval = CPXdualopt(lp->cplex_env, lp->cplex_lp);
         abort_if(rval, "CPXoptimize failed");
     }
@@ -388,6 +389,9 @@ int LP_add_cut(struct LP *lp, struct Row *cut)
         if (lp->cut_pool[i]->hash != cut->hash) continue;
         if (!compare_cuts(lp->cut_pool[i], cut))
         {
+            log_verbose("Discarding duplicate cut (same as cplex row %d)\n",
+                    lp->cut_pool[i]->cplex_row_index);
+
             free(cut->rmatval);
             free(cut->rmatind);
             free(cut);
diff --git a/src/params.h b/src/params.h
new file mode 100644
index 0000000..36998ea
--- /dev/null
+++ b/src/params.h
@@ -0,0 +1,10 @@
+#ifndef PROJECT_PARAMS_H
+#define PROJECT_PARAMS_H
+
+#define LOG_LEVEL LOG_LEVEL_DEBUG
+
+//#define ENABLE_COMB_INEQUALITIES
+
+//#define ALLOW_FRACTIONAL_SOLUTIONS
+
+#endif //PROJECT_PARAMS_H
diff --git a/src/util.h b/src/util.h
index f0ca093..57c9c01 100644
--- a/src/util.h
+++ b/src/util.h
@@ -2,6 +2,7 @@
 #define _PROJECT_UTIL_H_
 
 #include <string.h>
+#include "params.h"
 
 #define LOG_LEVEL_ERROR 10
 #define LOG_LEVEL_WARNING 20
@@ -9,8 +10,11 @@
 #define LOG_LEVEL_DEBUG 40
 #define LOG_LEVEL_VERBOSE 50
 
+<<<<<<< HEAD
 #define LOG_LEVEL LOG_LEVEL_DEBUG
 
+=======
+>>>>>>> 550b5f1912da4f50cd0bd0a7d2f19cdbf695b180
 #if LOG_LEVEL < LOG_LEVEL_VERBOSE
 #define log_verbose(...)
 #else
@@ -45,6 +49,10 @@
     fprintf(stderr, "%20s:%d " msg "\n", __FILE__, __LINE__); \
     rval = 1; goto CLEANUP; }
 
+#define abort_iff(cond, msg, ...) if(cond) { \
+    fprintf(stderr, "%20s:%d " msg "\n", __FILE__, __LINE__, __VA_ARGS__); \
+    rval = 1; goto CLEANUP; }
+
 #define swap(x, y) do \
    { unsigned char swap_temp[sizeof(x)]; \
      memcpy(swap_temp,&y,sizeof(x)); \