12 lines
512 B
Plaintext
12 lines
512 B
Plaintext
val IS_WEAK_SUBLIST_REC_def = Define `
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(IS_WEAK_SUBLIST_REC (l1 : 'a list) ([]:'a list) = T) /\
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(IS_WEAK_SUBLIST_REC [] (_::_) = F) /\
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(IS_WEAK_SUBLIST_REC (y::ys) (x::xs) = (
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(x = y) /\ IS_WEAK_SUBLIST_REC ys xs) \/ (IS_WEAK_SUBLIST_REC ys (x::xs)))`;
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val FILTER_BY_BOOLS_def = Define `
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FILTER_BY_BOOLS bl l = MAP SND (FILTER FST (ZIP (bl, l)))`
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val IS_WEAK_SUBLIST_FILTER_def = Define `IS_WEAK_SUBLIST_FILTER l1 l2 =
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?(bl : bool list). (LENGTH bl = LENGTH l1) /\ (l2 = FILTER_BY_BOOLS bl l1)`
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