[hoodcm]

Part of #5.

Check	Data checked	Why
equivalent_pair	Logical axioms	Two named classes aren't declared equivalent.

ROBOT's standard check, at ERROR. Nothing on main fails it, so no data changes. All tests pass.

[jclerman]

Nice. However, I'd enable this at ERROR. Any reason not to? WARN won't be visible unless people are manually checking, and I don't think we intend to have any logically-duplicate classes.

[jclerman]

NOTE we should also run this after reasoning.

[hoodcm]

Raised to ERROR.

On running it after reasoning: the robot reason step in CI already runs with --equivalent-classes-allowed asserted-only, which fails on any equivalence the reasoner infers. This check covers the asserted ones, so together they cover both.