Description: Order of concatenation does not affect homotopy class. (Contributed by Jeff Madsen, 19-Jun-2010) (Proof shortened by Mario Carneiro, 8-Jun-2014)
Ref | Expression | ||
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Hypotheses | pcoass.2 | |
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pcoass.3 | |
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pcoass.4 | |
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pcoass.5 | |
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pcoass.6 | |
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pcoass.7 | |
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Assertion | pcoass | |