2014-12-16 21:28:43 +00:00
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open eq
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definition concat_pV_p {A : Type} {x y z : A} (p : x = z) (q : y = z) : (p ⬝ q⁻¹) ⬝ q = p :=
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begin
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generalize p,
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2015-05-01 22:07:28 +00:00
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eapply (eq.rec_on q),
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2014-12-16 21:28:43 +00:00
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intro p,
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apply (eq.rec_on p),
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apply idp
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end
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