Lean.MVarId.liftReflToEq

Convert a goal of the form x ~ y into the form x = y, where ~ is a reflexive relation, that is, a relation which has a reflexive lemma tagged with the attribute [refl]. If this can't be done, returns the original MVarId.

def Mathlib.Tactic.rflTac : Lean.Elab.Tactic.TacticM Unit

This tactic applies to a goal whose target has the form x ~ x, where ~ is a reflexive relation, that is, a relation which has a reflexive lemma tagged with the attribute [refl].

def Lean.Expr.relSidesIfRefl? (e : Expr) : MetaM (Option (Name × Expr × Expr))

If e is the form @R .. x y, where R is a reflexive relation, return some (R, x, y). As a special case, if e is @HEq α a β b, return some (`HEq, a, b).