reduce

Reduce only against a closed set: what the text must cover is in hand and nothing unseen is coming. This runs inside one turn — nothing waits on the user.

Set the old wording aside. Take what the text must cover and derive the shortest statement that covers all of it — deleting sentences keeps whichever ones happened to be there, which is not the shortest way to cover the set.

If what it must cover has moved since the text was written — cases now in hand it was not derived on, an objective it was not written for — derive from the coverage as it stands today. What comes out is a new derivation of the current set, standing on its own. Between candidate statements, prefer the shortest one that covers everything over the one that keeps the original's shape.

Push the derived statement shorter, pass by pass. When a pass makes it stop covering something, it went too far — back off by the minimum that recovers it. The floor is where every remaining cut costs coverage; a clause that survives every pass is load-bearing.

Hand back two things: the reduced statement, and the name of anything that refused to get shorter. The statement is claimed to cover the set it was derived from, checked — everything outside that set is open.

What it must cover can't be stated or recovered → every cut is blind. Something unseen will meet it — a class no rule yet decides, or a rule that decides only the cases it came from → use widen skill.