Prolog Essentials

Test 1: X = f(a, b) succeeds — X is bound to the structure f(a, b) . Unification works with any term, not just numbers.
Test 2: f(X, b) = f(a, Y) matches corresponding arguments: X with a , b with Y. Both sides become f(a, b) .
Test 3 FAILS: a = b tries to make two different atoms identical — impossible. This is the core of unification: it only succeeds when terms can be made equal.
Test 4 SUCCEEDS: X = 3, X = 3 — after X is bound to 3, unifying X with 3 again just checks that 3 = 3 (trivially true).
Test 5 FAILS: X = 3, X = 4 — X is bound to 3, so X = 4 becomes 3 = 4 , which fails. Variables are single-assignment — this is the #1 difference from imperative languages.

Delete saved progress?

Do you want to delete all saved progress for this tutorial and reset the current step files?

Selecting No will just turn off auto-save — your progress is kept but won't be updated.

Reading aloud 1.0x