Description: If F is an extension sequence and A is an extension of the last element of F , then F + <" A "> is an extension sequence. (Contributed by Mario Carneiro, 1-Oct-2015)
Ref | Expression | ||
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Hypotheses | efgval.w | |
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efgval.r | |
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efgval2.m | |
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efgval2.t | |
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efgred.d | |
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efgred.s | |
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Assertion | efgsp1 | |