diff --git a/src/unit_tests/models/graph/kcoloring.rs b/src/unit_tests/models/graph/kcoloring.rs
index c710cdb32..7bfe2fc9a 100644
--- a/src/unit_tests/models/graph/kcoloring.rs
+++ b/src/unit_tests/models/graph/kcoloring.rs
@@ -178,3 +178,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_sat, jl_best, "KColoring satisfying solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Path graph: 0-1-2, 3-coloring
+    let problem = KColoring::<K3, _>::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]));
+    // Valid: neighbors have different colors
+    assert!(problem.is_valid_solution(&[0, 1, 0]));
+    // Invalid: adjacent vertices 0 and 1 have same color
+    assert!(!problem.is_valid_solution(&[0, 0, 1]));
+}
diff --git a/src/unit_tests/models/graph/max_cut.rs b/src/unit_tests/models/graph/max_cut.rs
index 4e2509f0c..3d7059c62 100644
--- a/src/unit_tests/models/graph/max_cut.rs
+++ b/src/unit_tests/models/graph/max_cut.rs
@@ -128,3 +128,12 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "MaxCut best solutions mismatch");
     }
 }
+
+#[test]
+fn test_cut_size_method() {
+    let problem = MaxCut::new(SimpleGraph::new(3, vec![(0, 1), (1, 2), (0, 2)]), vec![1, 2, 3]);
+    // Partition {0} vs {1, 2}: cuts edges (0,1)=1 and (0,2)=3
+    assert_eq!(problem.cut_size(&[0, 1, 1]), 4);
+    // All same partition: no edges cut
+    assert_eq!(problem.cut_size(&[0, 0, 0]), 0);
+}
diff --git a/src/unit_tests/models/graph/maximal_is.rs b/src/unit_tests/models/graph/maximal_is.rs
index 64ab76358..22069621a 100644
--- a/src/unit_tests/models/graph/maximal_is.rs
+++ b/src/unit_tests/models/graph/maximal_is.rs
@@ -163,3 +163,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "MaximalIS best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Path graph: 0-1-2
+    let problem = MaximalIS::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]), vec![1i32; 3]);
+    // Valid: {0, 2} is maximal (independent and no vertex can be added)
+    assert!(problem.is_valid_solution(&[1, 0, 1]));
+    // Invalid: {0} is independent but not maximal (vertex 2 can be added)
+    assert!(!problem.is_valid_solution(&[1, 0, 0]));
+}
diff --git a/src/unit_tests/models/graph/maximum_clique.rs b/src/unit_tests/models/graph/maximum_clique.rs
index 32f65b806..9ef849209 100644
--- a/src/unit_tests/models/graph/maximum_clique.rs
+++ b/src/unit_tests/models/graph/maximum_clique.rs
@@ -269,3 +269,18 @@ fn test_clique_problem() {
     assert_eq!(p.evaluate(&[1, 0, 0]), SolutionSize::Valid(1));
     assert_eq!(p.direction(), Direction::Maximize);
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Triangle: 0-1-2 all connected
+    let problem = MaximumClique::new(
+        SimpleGraph::new(3, vec![(0, 1), (1, 2), (0, 2)]),
+        vec![1i32; 3],
+    );
+    // Valid: all three form a clique
+    assert!(problem.is_valid_solution(&[1, 1, 1]));
+    // Now path graph: 0-1-2 (no 0-2 edge)
+    let problem2 = MaximumClique::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]), vec![1i32; 3]);
+    // Invalid: {0, 2} not adjacent
+    assert!(!problem2.is_valid_solution(&[1, 0, 1]));
+}
diff --git a/src/unit_tests/models/graph/maximum_independent_set.rs b/src/unit_tests/models/graph/maximum_independent_set.rs
index b5cc3d049..842870f14 100644
--- a/src/unit_tests/models/graph/maximum_independent_set.rs
+++ b/src/unit_tests/models/graph/maximum_independent_set.rs
@@ -161,3 +161,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "IS best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Path graph: 0-1-2
+    let problem = MaximumIndependentSet::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]), vec![1i32; 3]);
+    // Valid: {0, 2} is independent
+    assert!(problem.is_valid_solution(&[1, 0, 1]));
+    // Invalid: {0, 1} are adjacent
+    assert!(!problem.is_valid_solution(&[1, 1, 0]));
+}
diff --git a/src/unit_tests/models/graph/maximum_matching.rs b/src/unit_tests/models/graph/maximum_matching.rs
index a71a51215..745cc8050 100644
--- a/src/unit_tests/models/graph/maximum_matching.rs
+++ b/src/unit_tests/models/graph/maximum_matching.rs
@@ -153,3 +153,16 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "Matching best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Triangle: edges (0,1), (1,2), (0,2) — config is per edge
+    let problem = MaximumMatching::new(
+        SimpleGraph::new(3, vec![(0, 1), (1, 2), (0, 2)]),
+        vec![1i32; 3],
+    );
+    // Valid: select edge (0,1) only — no shared vertices
+    assert!(problem.is_valid_solution(&[1, 0, 0]));
+    // Invalid: select edges (0,1) and (1,2) — vertex 1 shared
+    assert!(!problem.is_valid_solution(&[1, 1, 0]));
+}
diff --git a/src/unit_tests/models/graph/minimum_dominating_set.rs b/src/unit_tests/models/graph/minimum_dominating_set.rs
index c99f3a733..432f4a280 100644
--- a/src/unit_tests/models/graph/minimum_dominating_set.rs
+++ b/src/unit_tests/models/graph/minimum_dominating_set.rs
@@ -158,3 +158,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "DS best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Path graph: 0-1-2
+    let problem = MinimumDominatingSet::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]), vec![1i32; 3]);
+    // Valid: {1} dominates all vertices (0 and 2 are neighbors of 1)
+    assert!(problem.is_valid_solution(&[0, 1, 0]));
+    // Invalid: {0} doesn't dominate vertex 2
+    assert!(!problem.is_valid_solution(&[1, 0, 0]));
+}
diff --git a/src/unit_tests/models/graph/minimum_vertex_cover.rs b/src/unit_tests/models/graph/minimum_vertex_cover.rs
index 509b5e803..396105fb5 100644
--- a/src/unit_tests/models/graph/minimum_vertex_cover.rs
+++ b/src/unit_tests/models/graph/minimum_vertex_cover.rs
@@ -144,3 +144,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "VC best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Path graph: 0-1-2
+    let problem = MinimumVertexCover::new(SimpleGraph::new(3, vec![(0, 1), (1, 2)]), vec![1i32; 3]);
+    // Valid: {1} covers both edges
+    assert!(problem.is_valid_solution(&[0, 1, 0]));
+    // Invalid: {0} doesn't cover edge (1,2)
+    assert!(!problem.is_valid_solution(&[1, 0, 0]));
+}
diff --git a/src/unit_tests/models/graph/traveling_salesman.rs b/src/unit_tests/models/graph/traveling_salesman.rs
index e1047e243..87d471227 100644
--- a/src/unit_tests/models/graph/traveling_salesman.rs
+++ b/src/unit_tests/models/graph/traveling_salesman.rs
@@ -222,3 +222,16 @@ fn test_brute_force_triangle_weighted() {
     assert_eq!(solutions[0], vec![1, 1, 1]);
     assert_eq!(problem.evaluate(&solutions[0]), SolutionSize::Valid(30));
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // K3 triangle: edges (0,1), (0,2), (1,2) — config is per edge
+    let problem = TravelingSalesman::new(
+        SimpleGraph::new(3, vec![(0, 1), (0, 2), (1, 2)]),
+        vec![1, 2, 3],
+    );
+    // Valid: select all 3 edges forms Hamiltonian cycle 0-1-2-0
+    assert!(problem.is_valid_solution(&[1, 1, 1]));
+    // Invalid: select only 2 edges — not a cycle
+    assert!(!problem.is_valid_solution(&[1, 1, 0]));
+}
diff --git a/src/unit_tests/models/satisfiability/sat.rs b/src/unit_tests/models/satisfiability/sat.rs
index 42f2e25f1..cd346f859 100644
--- a/src/unit_tests/models/satisfiability/sat.rs
+++ b/src/unit_tests/models/satisfiability/sat.rs
@@ -194,3 +194,16 @@ fn test_jl_parity_evaluation() {
         }
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // (x1 OR x2) AND (NOT x1 OR x3)
+    let problem = Satisfiability::new(
+        3,
+        vec![CNFClause::new(vec![1, 2]), CNFClause::new(vec![-1, 3])],
+    );
+    // Valid: x1=F, x2=T, x3=T → (T) AND (T) = T
+    assert!(problem.is_valid_solution(&[0, 1, 1]));
+    // Invalid: x1=T, x2=F, x3=F → (T) AND (F) = F
+    assert!(!problem.is_valid_solution(&[1, 0, 0]));
+}
diff --git a/src/unit_tests/models/set/maximum_set_packing.rs b/src/unit_tests/models/set/maximum_set_packing.rs
index 6f65c4d6b..8242c3a9f 100644
--- a/src/unit_tests/models/set/maximum_set_packing.rs
+++ b/src/unit_tests/models/set/maximum_set_packing.rs
@@ -136,3 +136,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "SetPacking best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Sets: {0,1}, {1,2}, {3,4}
+    let problem = MaximumSetPacking::<i32>::new(vec![vec![0, 1], vec![1, 2], vec![3, 4]]);
+    // Valid: select sets 0 and 2 (disjoint: {0,1} and {3,4})
+    assert!(problem.is_valid_solution(&[1, 0, 1]));
+    // Invalid: select sets 0 and 1 (share element 1)
+    assert!(!problem.is_valid_solution(&[1, 1, 0]));
+}
diff --git a/src/unit_tests/models/set/minimum_set_covering.rs b/src/unit_tests/models/set/minimum_set_covering.rs
index fa9036e54..c04aac0b0 100644
--- a/src/unit_tests/models/set/minimum_set_covering.rs
+++ b/src/unit_tests/models/set/minimum_set_covering.rs
@@ -106,3 +106,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "SetCovering best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Universe: {0,1,2,3}, Sets: {0,1}, {1,2}, {2,3}
+    let problem = MinimumSetCovering::<i32>::new(4, vec![vec![0, 1], vec![1, 2], vec![2, 3]]);
+    // Valid: all sets selected covers {0,1,2,3}
+    assert!(problem.is_valid_solution(&[1, 1, 1]));
+    // Invalid: only set 1 ({1,2}) doesn't cover 0 and 3
+    assert!(!problem.is_valid_solution(&[0, 1, 0]));
+}
diff --git a/src/unit_tests/models/specialized/biclique_cover.rs b/src/unit_tests/models/specialized/biclique_cover.rs
index 10cfbaacf..bb59df538 100644
--- a/src/unit_tests/models/specialized/biclique_cover.rs
+++ b/src/unit_tests/models/specialized/biclique_cover.rs
@@ -230,3 +230,16 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "BicliqueCover best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    use crate::topology::BipartiteGraph;
+    // Single edge (0,0) with 1 biclique
+    let graph = BipartiteGraph::new(1, 1, vec![(0, 0)]);
+    let problem = BicliqueCover::new(graph, 1);
+    // 2 vertices (left_0, right_0), 1 biclique → config length = 2
+    // Valid: both vertices in biclique 0 → covers edge (0,0)
+    assert!(problem.is_valid_solution(&[1, 1]));
+    // Invalid: only left vertex in biclique → doesn't form complete bipartite subgraph covering edge
+    assert!(!problem.is_valid_solution(&[1, 0]));
+}
diff --git a/src/unit_tests/models/specialized/circuit.rs b/src/unit_tests/models/specialized/circuit.rs
index e786ef196..6e75834d6 100644
--- a/src/unit_tests/models/specialized/circuit.rs
+++ b/src/unit_tests/models/specialized/circuit.rs
@@ -235,3 +235,18 @@ fn test_circuit_sat_problem() {
     // c=1, x=1, y=0: c = 1 AND 0 = 0 != 1 => not satisfied
     assert!(!p.evaluate(&[1, 1, 0]));
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // c = x AND y
+    let circuit = Circuit::new(vec![Assignment::new(
+        vec!["c".to_string()],
+        BooleanExpr::and(vec![BooleanExpr::var("x"), BooleanExpr::var("y")]),
+    )]);
+    let problem = CircuitSAT::new(circuit);
+    // Variables sorted: c, x, y
+    // Valid: c=1, x=1, y=1 (c = 1 AND 1 = 1)
+    assert!(problem.is_valid_solution(&[1, 1, 1]));
+    // Invalid: c=1, x=1, y=0 (c = 1 AND 0 = 0, but c=1)
+    assert!(!problem.is_valid_solution(&[1, 1, 0]));
+}
diff --git a/src/unit_tests/models/specialized/factoring.rs b/src/unit_tests/models/specialized/factoring.rs
index 1acd08928..ed6997037 100644
--- a/src/unit_tests/models/specialized/factoring.rs
+++ b/src/unit_tests/models/specialized/factoring.rs
@@ -96,3 +96,13 @@ fn test_jl_parity_evaluation() {
         assert_eq!(rust_best, jl_best, "Factoring best solutions mismatch");
     }
 }
+
+#[test]
+fn test_is_valid_solution() {
+    // Factor 15 = 3 × 5, 3 bits each
+    let problem = Factoring::new(3, 3, 15);
+    // Valid: 3 = [1,1,0], 5 = [1,0,1] → config = [1,1,0,1,0,1]
+    assert!(problem.is_valid_solution(&[1, 1, 0, 1, 0, 1]));
+    // Invalid: 2 = [0,1,0], 3 = [1,1,0] → 2*3=6 ≠ 15
+    assert!(!problem.is_valid_solution(&[0, 1, 0, 1, 1, 0]));
+}
diff --git a/src/unit_tests/variant.rs b/src/unit_tests/variant.rs
index 850bc15e0..90b582e28 100644
--- a/src/unit_tests/variant.rs
+++ b/src/unit_tests/variant.rs
@@ -243,7 +243,7 @@ fn test_kvalue_kn() {
 // --- Graph type VariantParam tests ---
 
 use crate::topology::HyperGraph;
-use crate::topology::{Graph, SimpleGraph, UnitDiskGraph};
+use crate::topology::{BipartiteGraph, Graph, PlanarGraph, SimpleGraph, UnitDiskGraph};
 
 #[test]
 fn test_simple_graph_variant_param() {
@@ -266,6 +266,20 @@ fn test_hyper_graph_variant_param() {
     assert_eq!(HyperGraph::PARENT_VALUE, None);
 }
 
+#[test]
+fn test_planar_graph_variant_param() {
+    assert_eq!(PlanarGraph::CATEGORY, "graph");
+    assert_eq!(PlanarGraph::VALUE, "PlanarGraph");
+    assert_eq!(PlanarGraph::PARENT_VALUE, Some("SimpleGraph"));
+}
+
+#[test]
+fn test_bipartite_graph_variant_param() {
+    assert_eq!(BipartiteGraph::CATEGORY, "graph");
+    assert_eq!(BipartiteGraph::VALUE, "BipartiteGraph");
+    assert_eq!(BipartiteGraph::PARENT_VALUE, Some("SimpleGraph"));
+}
+
 #[test]
 fn test_simple_graph_cast_to_parent() {
     let sg = SimpleGraph::new(3, vec![(0, 1), (1, 2)]);
diff --git a/tests/suites/reductions.rs b/tests/suites/reductions.rs
index 1dd7e76c7..314c8defd 100644
--- a/tests/suites/reductions.rs
+++ b/tests/suites/reductions.rs
@@ -422,8 +422,8 @@ mod topology_tests {
     }
 }
 
-// TruthTable integration tests moved to src/unit_tests/truth_table.rs
-// (truth_table module is now pub(crate))
+// TruthTable integration tests removed (module is now pub(crate));
+// equivalent coverage exists in src/unit_tests/truth_table.rs
 
 /// Tests for QUBO reductions against ground truth JSON.
 mod qubo_reductions {