Elimination Is Safe
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
Propagation deletes only values that appear in no solution — every deletion is a small proof, so nothing legal is ever lost.
Show
A value with no legal partner under some constraint cannot appear in any assignment that satisfies everything; striking it costs nothing.
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Safety belongs to the deletions, not the translation — a wrong constraint proves wrong things efficiently.