Your next idea starts here.

Choose a predicate, write your answer, and use the feedback to improve it.

Drafts stay in this browser. Save a file to move your progress.

predicate.alsALLOY

pred … {

Ln 1, Col 1UTF-8·Predicate body only

Live feedback

Your canonical form

The checker rewrites your predicate into this standard form for comparison. Select an edit to highlight the related parts.

Check your predicate to see its canonical form.

Model environmentREAD ONLY

The model's declarations and commands appear together below. The TODO marks the predicate body you write in the editor above.

Select an exercise to inspect its model.

Original model · preserved as supplied

Compare using

Compares simplified forms of your predicate and the saved correct answers.

A little feedback goes a long way.

Write your predicate to see how closely its structure matches a correct answer and which parts to review.

Correct answers, including the oracle, stay private. Feedback shows parts of your code and hints about which operators to review.

Your progress

0 checks

Each successful check is a new point on your path.

The distance uses the closest match among the saved correct answers, including the oracle. Zero means their canonical forms match. It does not prove that they behave the same in every case.

Check your predicate to compare its behavior with the oracle.

Drafts that pass the bounded behavioral checks may be retained privately for administrator review.

Your next idea starts here.

Predicate editor

Structural feedback

A little feedback goes a long way.

Your progress

Behavioral similarity score