counterexample

A friendly functional language for finding counterexamples 🎯

MIRROR of https://codeberg.org/catseye/Eightebed : A C-like language with explicit free which is nonetheless safe

Adversarial patch verification with executable evidence, minimized counterexamples, regression synthesis, and CI/VS Code integrations.

A 13-vertex disproof of the Annor–Howerton graph conjecture, with a structural proof, machine-readable witnesses, and exact verification

Proof that 20 glasses of Ouzo don't matter by Mathematical Induction

Lean 4 certificates for C5[K4] counterexamples to WOWII Graph Conjectures 63 and 85

A 12-vertex counterexample to Stanley’s claw-free Schur-positivity conjecture

a dynamic analysis tool to find interactions among configuration options in highly-configurable software.

An explicit C^4 counterexample to the Jacobian Conjecture via a normalized linear-times-cubic quartic factorization.

Exact counterexamples to a Lorentzianity conjecture for border-strip E-polynomials

Stochastic parallelised search for counter- and extreme examples to inequalities between "nonbities" of 2 polynomials with nonnegative coefficients and of their product, where a nonbity of a polynomial quantifies its "distinctiveness" from a {0,1}-one. Related to unfair 0-1-polynomials conjecture.

Explicit 14-vertex counterexample to Written on the Wall II Conjecture 200, with proof, exact verifiers, and Lean 4 formalization

An explicit-state model checker in ~2900 lines. Shortest counterexamples, no required dependencies, and UNDETERMINED is never a pass.

Counterexamples to Ashbaugh's higher-index PPW conjecture for Dirichlet Laplacian eigenvalue ratios, with exact-arithmetic verification.

Property-based testing plugin for tape-six powered by fast-check: t.prop() and t.scheduler() tester methods with structured counterexamples, seeds, and replay.

Exact Water Sort oracle and parallel search for a 5x16 counterexample

Teacher-controlled deterministic counterexample compiler for signed-integer subtraction

Exact counterexample (22 July 2026) and unbounded family (24 July 2026) for line-graph inertia Conjecture 4.12, with reproducible exact certificates.

First counterexample to Zhi-Wei Sun's 2018 conjecture (OEIS A303639): n = 800,322,180 — with machine-checkable certificates

Turns developer-approved SQLite migration promises into minimal, replayable counterexamples.