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Universal Algebra and Computational Complexity Lecture 3

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An obvious upper bound for SUB-MEM<br />

Algorithm:<br />

INPUT: A, S, b.<br />

S 0 := S<br />

For i = 1, . . . , n ( := |A|)<br />

S i := S i−1<br />

For each operation f (of arity r)<br />

For each (a 1 , . . . , a r ) ∈ (S i−1 ) r<br />

c := f (a 1 , . . . , a r )<br />

S i := S i ∪ {c}.<br />

Next i.<br />

OUTPUT: whether b ∈ S n .<br />

n loops<br />

T operations<br />

≤ n r instances<br />

Ross Willard (Waterloo) <strong>Algebra</strong> <strong>and</strong> <strong>Complexity</strong> Třešť, September 2008 8 / 31

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