intro h
case mp
X : Type
inst✝¹ : PartialOrder X
inst✝ : CompleteLattice X
x x' : X
⊢ x ≤ x' → Inf {x, x'} = x
case mp
X : Type
inst✝¹ : PartialOrder X
inst✝ : CompleteLattice X
x x' : X
h : x ≤ x'
⊢ Inf {x, x'} = x