lean2/tests/lean/hott/get_tac1.hlean

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Text

open eq
definition concat_pV_p {A : Type} {x y z : A} (p : x = z) (q : y = z) : (p ⬝ q⁻¹) ⬝ q = p :=
begin
generalize p,
eapply (eq.rec_on q),
intro p,
apply (eq.rec_on p),
apply idp
end