2014-10-24 05:40:15 +00:00
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import hott.path tools.tactic
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open path
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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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2014-10-25 20:36:38 +00:00
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apply (path.rec_on q),
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2014-10-24 05:40:15 +00:00
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intro p,
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2014-10-25 20:36:38 +00:00
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apply (path.rec_on p),
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2014-10-24 05:40:15 +00:00
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apply idp
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end
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