Global Games

Pick a single prediction out of a coordination game's many self-fulfilling equilibria by giving each player a private noisy signal of a common fundamental and deleting dominated strategies inward until one threshold cutoff survives.

Core Idea

A class of incomplete-information coordination games (Carlsson–van Damme 1993; Morris–Shin 1998) that selects a unique equilibrium where complete information leaves many. Each player gets a private noisy signal of a common unobserved fundamental; at extreme signals one action is dominant, and iterated deletion of dominated strategies inward from those regions pins down a single threshold strategy — act if and only if your signal falls on the calculable side of a cutoff.

Scope of Application

An equilibrium-selection method that lives wherever three ingredients recur: a base coordination game with strategic complementarities, a common unobserved fundamental, and a private-signal structure.

• Currency attacks — the originating case, with the attack threshold set by reserves, attack cost, and noise variance.
• Bank runs — a unique run threshold as a function of bank fundamentals (Goldstein–Pauzner).
• Sovereign-debt rollover crises — each creditor's decision keyed to beliefs about the others.
• Technology adoption under network externalities — unique adoption thresholds replace chicken-and-egg multiplicity.
• Political regime change — participation thresholds in protest keyed to beliefs about others.

Clarity

Global games dissolve the question that haunted coordination-game analysis: which self-fulfilling equilibrium do agents actually play? By perturbing the game with private noise, they supply the first mechanism-grounded selection — a calculable cutoff rather than an unsystematic focal-point guess. They also refute the fundamentals-versus-sentiment dichotomy, since the noise ties the outcome to the fundamental.

Manages Complexity

A coordination game under complete information is a swamp of self-fulfilling equilibria across a band of fundamentals. The framework collapses that swamp to one procedure with one output: solve for a single cutoff, a function of just the signal noise and the payoffs. A family of intractable crisis models becomes one tool deployed repeatedly.

Abstract Reasoning

The framework licenses equilibrium selection by construction (deducing rather than guessing the outcome), solve-for-the-cutoff reasoning that reads the crisis boundary off two inputs, and comparative statics on the threshold. A subtler move tracks public versus private information separately, since a public signal moves the threshold disproportionately.

Knowledge Transfer

A technical framework, so it transfers as method within the strategic-interaction substrate: the whole apparatus carries without translation across currency attacks, bank runs, debt rollovers, and regime change, which are co-instances of one object rather than analogies. It does not reach non-strategic systems — physical noise-induced-order phenomena share only a family resemblance. The portable selection insight belongs to the parent prime coordination_problem_and_equilibrium_selection.

Relationships to Other Abstractions

Current abstraction Global Games Domain-specific

Parents (4) — more general patterns this builds on

• Global Games is part of Bayesian Nash Equilibrium Domain-specific

  A Global Game contains a Bayesian equilibrium over signal-conditioned strategies; its uniqueness result selects one threshold member of that solution class.

• Global Games is part of Dominated Strategy Domain-specific

  Global Games contains iterated deletion of dominated strategies as the engine that moves inward from extreme-signal dominance regions.

• Global Games is part of Threshold Prime

  The selected equilibrium contains a cutoff that separates the signal region in which each of the two actions is optimal.

• Global Games is a decomposition of Coordination Problem and Equilibrium Selection Prime

  Removing private-signal game machinery leaves a method for selecting one outcome from several self-sustaining coordination equilibria.

Hierarchy paths (24) — routes to 15 parentless roots

• Global Games → Bayesian Nash Equilibrium → Nash Equilibrium → Equilibrium → Fixed Point

Show alternative paths (23)

Neighborhood in Abstraction Space

Global Games sits in a crowded region of the domain-specific corpus (1^st percentile for distinctiveness): several abstractions share nearly its structure, so a description that fits it tends to fit its neighbors too.

Family — Strategic Interaction & Game Theory (23 abstractions)

Nearest neighbors

• Dominated Strategy — 0.89
• Guess ⅔ of the Average — 0.89
• Subgame Perfect Equilibrium — 0.89
• Folk Theorem (Repeated Games) — 0.88
• Matching pennies — 0.88

Computed from structural-signature embeddings · 2026-07-12