lean2/tests/lean/run/beginend2.lean

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import hott.path tools.tactic
open path tactic
open path (induction_on)
definition concat_whisker2 {A} {x y z : A} (p p' : x ≈ y) (q q' : y ≈ z) (a : p ≈ p') (b : q ≈ q') :
(whiskerR a q) ⬝ (whiskerL p' b) ≈ (whiskerL p b) ⬝ (whiskerR a q') :=
begin
apply (induction_on b),
apply (induction_on a),
apply ((concat_1p _)⁻¹),
end