When Lisa Piccirillo solved a decades-old mystery about the “Conway knot,” she had to overcome the knot’s uncanny ability to hoodwink some of the most powerful tools mathematicians have devised. Known ...
Invariants should be well-formed formulas, that is, they should be logical statements (with a truth-value--true, of course), in the predicate calculus or rigorous English. A good invariant is a ...