diff --git a/colored_pentagon_contractions.py b/colored_pentagon_contractions.py
new file mode 100644
index 0000000..c0ff7a0
--- /dev/null
+++ b/colored_pentagon_contractions.py
@@ -0,0 +1,193 @@
+"""Example: colored pentagon reduction on a random 20-vertex triangulation."""
+import hashlib
+import json
+import base64
+from collections import defaultdict
+from pathlib import Path
+from typing import Any, cast, TypedDict, Literal
+from sage.all import graphs, Graph  # type: ignore[attr-defined]  # pylint: disable=no-name-in-module
+from lib.tutte_embedding import tutte_embedding
+from lib.planar_embedding import outer_face, get_embedding_from_pos
+from lib.colored_graphs import ColoredGraphId, VertexColoring, save_colored_graph
+
+DIR = Path(__file__).parent
+PALETTE = ['red', 'blue', 'green', 'yellow']
+
+class Operation(TypedDict):
+    """Information about a change made to a (colored) graph"""
+    name: Any
+    meta: Any
+    source_graph: Graph
+    source_canon_id: ColoredGraphId
+    result_graph: Graph
+    result_coloring: VertexColoring
+    result_canon_id: ColoredGraphId
+
+def colored_graph_id_to_string(cid: ColoredGraphId) -> str:
+    return f"{cid['graph_id']} {cid['coloring_id']}"
+
+def op_to_transform_id(op: Operation) -> str:
+    return f"{colored_graph_id_to_string(op['source_canon_id'])} -> {colored_graph_id_to_string(op['result_canon_id'])}"
+
+def operation_sequence_id(ops: list[Operation]) -> str:
+    joined = "\n".join(op_to_transform_id(op) for op in ops)
+    return hashlib.sha256(joined.encode()).hexdigest()
+
+def _neighbors_form_cycle(g: Graph, v: Any) -> bool:
+    """Return True if the neighbors of v induce a cycle in g."""
+    return bool(cast(Graph, g.subgraph(g.neighbors(v))).is_cycle())
+
+class PluckMeta(TypedDict):
+    """Meta information about the pluck operation"""
+    v0: Any
+
+class PluckOperation(Operation):
+    """Info about an operation in which a vertex v0 and its incident edges is removed from G"""
+    name: Literal['pluck']
+    meta: PluckMeta
+
+def pluck(g: Graph, coloring: VertexColoring, v0: Any) -> tuple[Graph, VertexColoring]:
+    """Delete v0 and all its incident edges from g"""
+    g_prime = g.copy()
+    g_prime.delete_vertex(v0)
+    if (pos := g.get_pos()) is not None:
+        g_prime.set_pos({v: p for v, p in pos.items() if v != v0})
+        g_prime.set_embedding(get_embedding_from_pos(g_prime))
+    coloring_prime = coloring.copy()
+    del coloring_prime[v0]
+    return g_prime, coloring_prime
+
+
+class SquishMeta(TypedDict):
+    """Meta information about the squish operation"""
+    v0: Any
+    v_merged: list[Any]
+
+class SquishOperation(Operation):
+    """
+    Info about an operation in which two same colored neighbors of a vertex v0 are merged
+    into v0
+    """
+    name: Literal['squish']
+    meta: SquishMeta
+
+def squish(g: Graph, coloring: VertexColoring, v0: Any) -> tuple[Graph, VertexColoring, Any, Any]:
+    """
+    Contract two same-colored neighbors of v0 into v0 and return a new valid
+    coloring along with the new graph.
+    NOTE: assumes g is a maximal planar graph
+    """
+    neighbor_by_color: defaultdict[Any, list[Any]] = defaultdict(list)
+    for v in g.neighbors(v0):
+        neighbor_by_color[coloring[v]].append(v)
+
+    v1, v2 = next(
+        (vs[0], vs[1]) for vs in neighbor_by_color.values() if len(vs) >= 2
+    )
+
+    g_prime = g.copy()
+    g_prime.merge_vertices([v0, v1, v2])
+    if (pos := g.get_pos()) is not None:
+        g_prime.set_pos({v: p for v, p in pos.items() if v not in (v1, v2)})
+        g_prime.set_embedding(get_embedding_from_pos(g_prime))
+    coloring_prime = {v: c for v, c in coloring.items() if v not in (v1, v2)}
+    coloring_prime[v0] = coloring[v1]
+    return g_prime, coloring_prime, v1, v2
+
+
+ReduceOperation = SquishOperation | PluckOperation
+
+def reduce(
+    g: Graph,
+    coloring: VertexColoring,
+    source_canon_id: ColoredGraphId,
+    op_sequence: list[ReduceOperation] | None = None,
+) -> list[ReduceOperation]:
+    """Repeatedly apply pluck/squish reductions until no candidates remain."""
+    if op_sequence is None:
+        op_sequence = []
+
+    print(f"Coloring: {coloring}")
+
+    degree_4_candidates: list[Any] = []
+    degree_5_candidates: list[Any] = []
+
+    for v in g.vertices():
+        if g.degree(v) == 3 and _neighbors_form_cycle(g, v):
+            result_graph, result_coloring = pluck(g, coloring, v)
+            print(f"\nG' (after pluck v0={v}): {result_graph.order()} vertices, {result_graph.size()} edges")
+            _, _, result_canon_id = save_colored_graph(result_graph, result_coloring)
+            op_sequence.append(PluckOperation(name='pluck', meta=PluckMeta(v0=v), source_graph=g, source_canon_id=source_canon_id, result_graph=result_graph, result_coloring=result_coloring, result_canon_id=result_canon_id))
+            return reduce(result_graph, result_coloring, result_canon_id, op_sequence)
+        if g.degree(v) == 4 and _neighbors_form_cycle(g, v):
+            degree_4_candidates.append(v)
+        elif g.degree(v) == 5 and _neighbors_form_cycle(g, v):
+            degree_5_candidates.append(v)
+
+    if degree_4_candidates:
+        v0 = degree_4_candidates[0]
+        result_graph, result_coloring, v1, v2 = squish(g, coloring, v0)
+        print(f"Shared-color neighbors: v1={v1}, v2={v2}  (color {coloring[v1]})")
+        print(f"\nG' (after squish v0={v0}): {result_graph.order()} vertices, {result_graph.size()} edges")
+        _, _, result_canon_id = save_colored_graph(result_graph, result_coloring)
+        op_sequence.append(SquishOperation(name='squish', meta=SquishMeta(v0=v0, v_merged=[v1, v2]), source_graph=g, source_canon_id=source_canon_id, result_graph=result_graph, result_coloring=result_coloring, result_canon_id=result_canon_id))
+        return reduce(result_graph, result_coloring, result_canon_id, op_sequence)
+
+    if degree_5_candidates:
+        v0 = degree_5_candidates[0]
+        result_graph, result_coloring, v1, v2 = squish(g, coloring, v0)
+        print(f"Shared-color neighbors: v1={v1}, v2={v2}  (color {coloring[v1]})")
+        print(f"\nG' (after squish v0={v0}): {result_graph.order()} vertices, {result_graph.size()} edges")
+        _, _, result_canon_id = save_colored_graph(result_graph, result_coloring)
+        op_sequence.append(SquishOperation(name='squish', meta=SquishMeta(v0=v0, v_merged=[v1, v2]), source_graph=g, source_canon_id=source_canon_id, result_graph=result_graph, result_coloring=result_coloring, result_canon_id=result_canon_id))
+        return reduce(result_graph, result_coloring, result_canon_id, op_sequence)
+
+    print("DONE")
+    return op_sequence
+
+
+G = next(graphs.planar_graphs(20, minimum_degree=5))
+print(f"G: {G.order()} vertices, {G.size()} edges")
+print(f"Degree sequence: {sorted(G.degree_sequence(), reverse=True)}")
+starting_coloring_classes = G.coloring()
+starting_coloring = {v: i for i, cls in enumerate(starting_coloring_classes) for v in cls}
+_, _, initial_canon_id = save_colored_graph(G, starting_coloring)
+G.is_planar(set_embedding=True, set_pos=True)
+
+def strip_graphs(obj: Any) -> Any:
+    if isinstance(obj, dict):
+        return {k: strip_graphs(v) for k, v in obj.items() if not isinstance(v, Graph)}
+    if isinstance(obj, list):
+        return [strip_graphs(v) for v in obj]
+    return obj
+
+def plot_to_data_uri(g: Graph, coloring: VertexColoring) -> str:
+    import tempfile
+    vertex_colors: defaultdict[str, list[Any]] = defaultdict(list)
+    for v, c in coloring.items():
+        vertex_colors[PALETTE[c]].append(v)
+    if g.get_pos() is None:
+        g.is_planar(set_embedding=True, set_pos=True)
+    g.set_pos(tutte_embedding(g, outer_face(g)))
+    with tempfile.NamedTemporaryFile(suffix='.png', delete=True) as f:
+        g.plot(vertex_colors=dict(vertex_colors)).save(f.name)
+        png_bytes = Path(f.name).read_bytes()
+    return f"data:image/png;base64,{base64.b64encode(png_bytes).decode()}"
+
+def save_operation_sequence(op_sequence: list[ReduceOperation], g: Graph, coloring: VertexColoring) -> str:
+    """Save op_sequence as JSON and Markdown under data/operations/<seq_id>. Returns the sequence id."""
+    op_seq_id = operation_sequence_id(op_sequence)
+    op_dir = DIR / "data" / "operations" / op_seq_id
+    op_dir.mkdir(parents=True, exist_ok=True)
+    (op_dir / "colored_pentagon_contractions.json").write_text(json.dumps(strip_graphs(op_sequence), indent=2))
+    md_lines = [f"## start\n\n![start]({plot_to_data_uri(g, coloring)})"]
+    for op in op_sequence:
+        meta_json = json.dumps(op['meta'])
+        md_lines.append(f"## {op['name']} {meta_json}\n\n![b]({plot_to_data_uri(op['result_graph'], op['result_coloring'])})")
+    (op_dir / "colored_pentagon_contractions.md").write_text("\n".join(md_lines) + "\n")
+    return op_seq_id
+
+op_sequence = reduce(G, starting_coloring, initial_canon_id)
+print("\nOp sequence:")
+print(json.dumps(strip_graphs(op_sequence), indent=2))
+save_operation_sequence(op_sequence, G, starting_coloring)
diff --git a/colored_pentagon_reduction/paper.aux b/colored_pentagon_contractions/paper.aux
similarity index 100%
rename from colored_pentagon_reduction/paper.aux
rename to colored_pentagon_contractions/paper.aux
diff --git a/colored_pentagon_reduction/paper.fdb_latexmk b/colored_pentagon_contractions/paper.fdb_latexmk
similarity index 100%
rename from colored_pentagon_reduction/paper.fdb_latexmk
rename to colored_pentagon_contractions/paper.fdb_latexmk
diff --git a/colored_pentagon_reduction/paper.fls b/colored_pentagon_contractions/paper.fls
similarity index 100%
rename from colored_pentagon_reduction/paper.fls
rename to colored_pentagon_contractions/paper.fls
diff --git a/colored_pentagon_reduction/paper.log b/colored_pentagon_contractions/paper.log
similarity index 100%
rename from colored_pentagon_reduction/paper.log
rename to colored_pentagon_contractions/paper.log
diff --git a/colored_pentagon_reduction/paper.pdf b/colored_pentagon_contractions/paper.pdf
similarity index 100%
rename from colored_pentagon_reduction/paper.pdf
rename to colored_pentagon_contractions/paper.pdf
diff --git a/colored_pentagon_reduction/paper.synctex.gz b/colored_pentagon_contractions/paper.synctex.gz
similarity index 100%
rename from colored_pentagon_reduction/paper.synctex.gz
rename to colored_pentagon_contractions/paper.synctex.gz
diff --git a/colored_pentagon_reduction/paper.tex b/colored_pentagon_contractions/paper.tex
similarity index 100%
rename from colored_pentagon_reduction/paper.tex
rename to colored_pentagon_contractions/paper.tex