A local-search approach to recognizing dominant strategies

Linchen Zhang proposes a way to assess whether a mechanism makes a dominant strategy easier to find: look at the paths available through small improvements.

What the study found

In an arXiv preprint, Zhang introduces local improvement solvability, a criterion based on a “neighbor relation” between strategies. A mechanism meets the criterion if repeatedly moving to an improving neighboring strategy always reaches a dominant strategy—a strategy that performs at least as well as alternatives regardless of others’ actions.

The abstract states that strategy-proofness corresponds to the criterion under the coarsest neighbor relation, while many classical mechanisms satisfy it under finer relations. For extensive-form mechanisms without duplicate dominant strategies, Zhang says the criterion using one-situation neighbors is strict action-proofness, distinct from obvious strategy-proofness.

Why it matters

A dominant strategy can exist without participants recognizing or choosing it. Zhang argues that comparisons between neighboring strategies may reduce the need to reason across contingencies and simplify the search through available choices, even when there is only one contingency.

For mechanisms that implement the same outcomes and satisfy local improvement solvability, the criterion predicts more dominant-strategy play when the local comparison is salient. This is a prediction about behavior, not evidence in the abstract that participants actually behave that way.

Limits and unknowns

The abstract does not identify the classical mechanisms covered, provide the formal definitions or proofs, or explain how salience would be measured. It also does not describe an experiment or empirical test of the behavioral prediction. The strength and practical scope of the results therefore cannot be assessed from the abstract alone.

Read the research

Authors: Linchen Zhang

Published: 2026-10-29

Source basis: Based on the abstract only

Original abstract

Strategy-proofness is the traditional standard for predictable behavior, yet participants often fail to play dominant strategies. Most existing simplicity concepts attribute these failures to the cost of contingent reasoning, which they lower by comparing the worst case of the dominant strategy with the best case of an alternative. I argue that there is another approach, one that makes more use of the structure of the strategy set, which I formalize as a neighbor relation. Comparing neighboring strategies can reduce the need for contingent reasoning, and, even with a single contingency, it can simplify the search through the strategy set. I introduce a new simplicity criterion: a mechanism is local improvement solvable under a neighbor relation if repeatedly moving to an improving neighbor always reaches a dominant strategy. Strategy-proofness is the criterion under the coarsest relation, and many classical mechanisms satisfy it under finer ones. In extensive-form mechanisms without duplicate dominant strategies, the criterion under one-situation neighbors is strict action-proofness, which is distinct from obvious strategy-proofness. Among local improvement solvable mechanisms that implement the same outcomes, the criterion predicts more dominant-strategy play where the local comparison is salient.

This article is an AI-generated adaptation, not a substitute for the original research. Preprints may not have been peer reviewed; AI can make mistakes.