intro hor
case mpr
B : State → Prop
S T : Stmt
s : State
Us : Stmt × State
⊢ B s ∧ Us = (S, s) ∨ ¬B s ∧ Us = (T, s) → (Stmt.ifThenElse B S T, s) ⇒ Us
case mpr
B : State → Prop
S T : Stmt
s : State
Us : Stmt × State
hor : B s ∧ Us = (S, s) ∨ ¬B s ∧ Us = (T, s)
⊢ (Stmt.ifThenElse B S T, s) ⇒ Us