calc
  lengthOfTNode Z ≤ lengthOfTNode c := endNodesOfLEQ Z_in_ZS
  _ < lengthOfTNode LR := this
case intro.intro.intro.intro
Z LR : TNode
a✝ : List TNode
lrApp : LocalRuleApp LR a✝
subTabs : (c : TNode) → c ∈ a✝ → LocalTableau c
c : TNode
c_in_C : c ∈ a✝
Z_in_ZS : Z ∈ endNodesOf ⟨c, subTabs c ⋯⟩
this : lengthOfTNode c < lengthOfTNode (LR.1, LR.2)
⊢ lengthOfTNode Z < lengthOfTNode LR
no goals