---
title: "Why Is Perpetual Chase Harder to Prove Than Perpetual Check? · Xiangqi Master"
description: "Check is a fact you can read straight off the board on every move. Chase depends on judging intent and available alternatives, which is why it needs a casebook of worked examples rather than a single clean rule."
url: https://xiangqimaster.com/blog/why-is-perpetual-chase-harder-to-prove-than-perpetual-check
updated: 2026-09-23
source: Xiangqi Master (https://xiangqimaster.com)
license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
---

# Why is a perpetual chase claim generally harder to prove than a perpetual check claim?

These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.

> Direct answer
>
> **Because check is an objective fact and chase is a judgement call.** Whether a piece is in check on a given move is completely unambiguous, either it is attacked with no legal escape from that attack or it is not. Whether a piece is being illegitimately chased depends on whether the chasing player had a genuine alternative and chose not to take it, a question about intent and available options that has to be judged case by case.

## What makes check simple to adjudicate

A check claim only ever needs the current position: is the piece attacked, does the attack persist move after move without variation. Nothing about the surrounding position's purpose matters, only the bare fact of the repeated attack.

## What makes chase genuinely harder

A chase claim requires asking whether the chasing piece was doing something else useful at the same time, whether the chased piece could simply move to safety, and whether the pattern is truly forced repetition or coincidental. Those are exactly the kind of borderline cases that led to the WXF building a casebook of worked examples rather than trying to write one clean rule that covers everything.

## Related questions

Is this why some cases are still genuinely disputed even among strong engines?

Yes, a handful of classic diagrams in the casebook are known to be judged differently by different strong engines, precisely because of this ambiguity.

Does this mean perpetual chase rulings are inconsistent?

Not inconsistent exactly, but they rely on precedent and judgement in a way perpetual check simply does not need to.

## Related xiangqi resources

Perpetual check and chase

Repetition is adjudicated, not automatically drawn

Editorial standards

How these answers are checked

Xiangqi rules

The complete reference, rule by rule

## Try it on a real board

Reading an answer is one thing; playing it is another. Free, instant, and nothing to install.