In a goal of the form tfae [a₀, a₁, a₂], tfae_have : i → j creates the assertion aᵢ → aⱼ. The other possible notations are tfae_have : i ← j and tfae_have : i ↔ j. The user can also provide a label for the assertion, as with have: tfae_have h : i ↔ j.

Finds all implications and equivalences in the context to prove a goal of the form tfae [...].