MULTIWAY EFFECTIVE STACKS — PUBLIC METHOD
Created 2026-09-06 by GTO Gecko / GTO Solutions AS.
Article: https://gtogecko.com/blog/multiway-effective-stacks

Question: which remaining-stack amounts can named players match at an aligned
postflop street-start checkpoint? This educational utility is separate from
GTO Gecko app data. Inputs and examples are synthetic. No private data,
measured player results, random samples or random seed are involved.

Use stack-map.html in a browser. It accepts two to nine seats with chips behind,
current-street contributions, and active/folded/all-in status. All current-street
contributions must be zero; it deliberately does not solve midstreet accounting.
At this checkpoint, each active pair's ceiling is min(S_i,S_j). A player's
largest potentially matched new contribution is min(S_i,max(other active S)).
Pairwise ceilings overlap: do not sum them. Zero behind removes future betting
capacity, not existing pot eligibility. A folded player's committed chips remain
in the pot. Neither formula settles an existing pot or recommends an action.

Files:
  stack-map.html — standalone browser aid, no network requests or persistence
  cases.json — six checked examples and a separate midstreet counterexample
  verify.py — standard-library Python reference and deterministic checks
  stack-map.svg — original diagram; numeric equivalent is in the article table
  SHA256SUMS — raw-byte hashes of the four files above and this README

REPRODUCE
Download these files into one folder, keeping their names. Use Python 3.10+:
  python verify.py
  python -O verify.py
Both must print PASS. The checker locates cases.json next to itself, independent
of the working directory. It uses explicit exceptions, so optimized Python does
not remove the checks. The reference uses pair minima and a max-opponent cap;
an exhaustive 1..8bb three-seat integer-layer construction checks the same
relationships by shared chip layers and their union. Six cases also receive
seat-order and positive unit-scaling checks. Invalid inputs are rejected.
Browser behavior is verified separately in the publication QA evidence.

LIMITS
The examples use no-limit Hold'em; the map is a capacity identity, not a legal
wager selector. It omits pot size, cards, ranges, positions' strategic effects,
prior contributions, raise rights, side-pot division, rake, antes and tournament
payout valuation. These omissions prevent it from being a solver or a call-price
calculator. Before preflop study, check whether a scenario's depth label means
chips before posts, after posts, or at another specified starting point.
Floating-point browser values may round; displayed values are for study, not
cashier or tournament settlement. No learning or financial outcome is claimed.

Primary sources, accessed 2026-09-06:
https://gtowizard.com/en/glossary/effective-stack/
https://www.pokerstars.com/poker/games/rules/

The code, synthetic data and diagram were created for this article.
No third-party article text or imagery is included.