Strategy · step 5 of 5

What-if chains

When every simpler technique is silent, pick a suspicious square and interrogate it: suppose a cat sat here — then what?

A what-if chain is not guessing. You never commit to the hypothesis; you follow its consequences with the same forced logic as always, and the payoff is a proof by contradiction:

• Suppose a cat sits at D4.
• Its shadow crosses out row 4, column D, and the ring around it…
• …which leaves the teal region a single square, at B5 — so teal’s cat is forced there…
• …whose shadow wipes out every remaining square of the yellow region. Yellow is homeless.
• Contradiction — so D4 can never hold a cat. Cross it out and continue normally.

One cross rarely sounds like much, but chains fire exactly when the board is jammed — and the square that survives interrogation-worthy suspicion is usually load-bearing. One proven cross typically cascades: a forced move, a shadow, and suddenly the simple techniques are alive again.

Choosing which square to interrogate

• Crowded intersections — squares whose shadow would hit several nearly-dead regions at once (the same instinct as the color squeeze, one level deeper).
• Small regions’ candidates — testing one of a region’s last two squares settles the region either way: contradiction crosses it, no contradiction tells you nothing but cost little.
• Keep chains shallow. If a hypothesis needs six moves to die, you probably missed a simpler deduction — go back down the ladder.

Know when you’re past the human line

Some computer-generated boards — Meowdoku’s endless mode is notorious for it — occasionally require chains no human would enjoy finding. MeowSolver is honest about this: hints flag when a deduction sits beyond the human line, tell you how long the rough patch lasts, and offer a guaranteed cat placement to skip it. Insisting on solving those stretches manually is a valid lifestyle choice, but it is a choice.

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