Tarski's World is a computer-based introduction to first-order logic written by Jon Barwise and John Etchemendy.
It is named after the mathematical logician Alfred Tarski.
The package includes a book, which serves as a textbook and manual, and a computer program which together serve as an introduction to the semantics of logic through games in which simple, three-dimensional worlds are populated with various geometric figures and these are used to test the truth or falsehood of first-order logic sentences.
The program is also included in Language, Proof and Logic package.
[1][2][3][4][5] The programme was later extended into Hyperproof.