mathlib documentation

tactic.split_ifs

Simp set for if-then-else statements

Splits all if-then-else-expressions into multiple goals.

Given a goal of the form g (if p then x else y), split_ifs will produce two goals: p ⊢ g x and ¬p ⊢ g y.

If there are multiple ite-expressions, then split_ifs will split them all, starting with a top-most one whose condition does not contain another ite-expression.

split_ifs at * splits all ite-expressions in all hypotheses as well as the goal.

split_ifs with h₁ h₂ h₃ overrides the default names for the hypotheses.