ICM Out! Better Tournament Strategy from Computed Continuations, vs. Solvers and LLMs

2026-08-10Artificial Intelligence

Artificial IntelligenceComputer Science and Game TheoryMultiagent Systems
AI summary

The authors explain that the common method called Independent Chip Model (ICM) for evaluating poker tournament strategies misses some important game details, like turn order and pressure on players with fewer chips. They propose a new method, Strategic-Continuation Optimization (SCO), which considers future possible outcomes and adjusts strategies accordingly. When tested in a simulated three-player poker tournament, SCO made noticeably different and better strategic choices, leading to higher expected winnings than ICM-based strategies. Their results suggest that ICM may not always provide the best foundation for building poker tournament strategies.

Independent Chip Model (ICM)poker tournamentstrategy optimizationprize equitygame theorystack sizefinite tournament modelpolicy constructionelimination pressure
Authors
Boning Li, Longbo Huang
Abstract
The Independent Chip Model (ICM) converts tournament chips into reference prize equity, and policies are routinely constructed against those values. Because ICM reads only stack sizes, it omits action order, blind obligations, and seat rotation, and it does not price the elimination pressure a big stack puts on the short stacks it can bust. Those omissions can alter the successor-state contrasts that determine a move. We introduce Strategic-Continuation Optimization (SCO), a policy-construction method that enumerates current-hand outcomes, maps them to successor states, prices those states with continuation values computed from the finite tournament model, and optimizes and freezes the resulting current-hand policy. The fixed-ICM comparison policy changes one thing only: the same optimizer solves the same game with successor states priced by analytic ICM, so the two policies differ only through that pricing. We evaluate the resulting policies in a three-player jam/fold tournament with a \$1M prize pool. Relative to the frozen strategic-continuation benchmark, analytic ICM has \$9{,}036 mean absolute value error across all 2,838 state--seat entries. That value error rewrites the ranges it prices: measured against each decision point's own fixed-ICM jam range, SCO moves the jam frequency by an average of 14.08\%. To price those different moves, we compare all 946 states and three policy owners while changing only the focal policy and holding both opponents and the continuation evaluator fixed. The policy produced by SCO earns \$214.33 more prize equity per hand on average and is favored in 2,433 of 2,838 matched units. The ordering survives replacing the solver-built opponent with two LLMs and with a family of non-modeling threshold players. This value-to-policy-to-cost chain shows directly when ICM becomes an inadequate objective for tournament strategy construction.