How to solve a World

Place every piece so every sentence is true. Start with the sentences that force a placement.

T∃x (Cube(x)∧Adjoins(x, b))

Start with the most demanding sentence. Some cube must touch b, and a is the only cube, so put them side by side.

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How it works

A World puzzle gives you pieces and sentences. You win when every piece is on the board and every sentence is true.

Sentences about named pieces and ∃ sentences tell you where things must go. ∀ and ¬∃ sentences only rule places out, so check them last.

Place the named pieces first.
Most sentences mention them.
∃ sentences force placements. ∀ sentences rule places out.
Tap a false sentence to see its culprit.
The highlighted piece is the one to move.

0 of 3 right

Question 1

∃x (Cube(x)∧Adjoins(x, b))

Question 2

∀x (Tet(x)→FrontOf(x, a))

Question 3

¬∃x (Tet(x)∧FrontOf(x, a))