intro s t
B : State → Prop
S : Stmt
⊢ Stmt.ifThenElse B (S; Stmt.whileDo B S) Stmt.skip ~ Stmt.whileDo B S
B : State → Prop
S : Stmt
s t : State
⊢ (Stmt.ifThenElse B (S; Stmt.whileDo B S) Stmt.skip, s) ⟹ t ↔ (Stmt.whileDo B S, s) ⟹ t