# SICStus Prolog "spdet" utility

Is unwanted backtracking hurting your application performance? Getting some puzzling answers that should not be there? SICStus Prolog includes a determinacy checker, spdet, originally written by Dave Bowen and Peter Schachte, for spotting non-deterministic predicates. A must have tool. Have you tried it recently in your code? You might be surprised by the results.