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Paper: Integer Reduction via Petri Net ODE Equilibrium

We've written up the integer reduction technique as a formal paper.

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The paper proves what the blog posts demonstrated experimentally: when you build an analysis net with catalytic source places and drain transitions, then run mass-action ODE to equilibrium, the steady-state concentrations are exact reciprocals of drain counts. No iterative eigenvector computation, no coupled fixed-point convergence — each accumulator obeys an independent ODE with a closed-form solution.

What's in the paper

The decoupling lemma. Each accumulator place obeys \dot{x}_i = 1 - n_i x_i, where n_i is the number of drain transitions. The ODEs are fully decoupled — source places hold constant concentration because the play transitions are catalytic. Equilibrium is x_i^* = 1/n_i, available in closed form.

The integer reduction theorem. After normalizing by the minimum concentration, strategic values are V_i = n_\text{max} / n_i — exact positive rationals determined entirely by net topology. When drain counts divide evenly, the values are integers.

Four experimental validations:

Game Topology Distinct Levels Max:Min
Tic-tac-toe (3×3, 5×5, 7×7) Square grid, full-line wins 3 2:1
Poker hand rankings Frequency-weighted drains 9 32:1
Connect Four (7×6) Rectangular grid, 4-in-a-row 9 4.33:1
Hex (5×5) Hexagonal grid, shortest paths 7 16:1

ZK integration. The same incidence matrix that defines the ODE system provides the constraint structure for Groth16 zero-knowledge proofs of game-state transitions — a unified pipeline from strategic analysis to on-chain verification.

The new results: Connect Four and Hex

The earlier blog posts covered tic-tac-toe and poker. The paper adds two games with richer topology.

Connect Four

A 7×6 grid with 69 win lines (all 4-in-a-row segments: horizontal, vertical, both diagonals). The drain count matrix:

 3   4   5   7   5   4   3
 4   6   8  10   8   6   4
 5   8  11  13  11   8   5
 5   8  11  13  11   8   5
 4   6   8  10   8   6   4
 3   4   5   7   5   4   3

The center column dominates at every row — matching the well-known heuristic that column 4 is the strongest opening move. The peak cells (rows 2–3, column 3) have drain count 13 vs. 3 for corners, giving a 4.33:1 value ratio. Nine distinct drain-count levels, compared to tic-tac-toe's three.

Hex

A 5×5 hexagonal board with path-based win conditions. Instead of fixed-length lines, a player wins by forming any path of adjacent cells connecting opposite edges. We enumerate all 96 shortest winning paths (48 top-to-bottom + 48 left-to-right) and create drains from path membership. The drain count matrix:

 2   7  15  23  32
 7  16  26  32  23
15  26  32  26  15
23  32  26  16   7
32  23  15   7   2

The striking result: the five cells on the anti-diagonal all share the maximum value of 16.0. This anti-diagonal is the "bridge" connecting both pairs of opposite edges — the most strategically contested territory in Hex. The board exhibits exact 180° rotation symmetry (V_{r,c} = V_{4-r,4-c}), and the 16:1 value ratio is the largest among all tested games.

Why this matters

Exactness without search. The values aren't heuristic approximations — they're provably exact rationals determined by topology alone. No game tree, no Monte Carlo sampling, no neural network.

Generality. The technique works across square grids (tic-tac-toe), non-square grids (Connect Four), frequency-weighted domains (poker), and non-Cartesian topology (Hex). The constraint type can be fixed-length lines, variable-length segments, or shortest paths.

Dual use. The incidence matrix serves both the continuous analysis (ODE equilibrium for strategic values) and the discrete proof system (Groth16 ZK proofs for game-state transitions). One mathematical object, two applications.

The paper, tests, and ODE solver are all in pflow-rs.

Read the paper (PDF)

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