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I know that the CIRCUIT VALUE problem is P-complete. In the CIRCUIT VALUE problem the input is a Boolean circuit together with an input to this circuit, and the answer is the evaluation of the given circuit on the given input.

I wish to know if the problem of evaluating a Boolean formula on a given assignment is also P-complete. From one hand, it seems that a Boolean circuit and a Boolean formula are very similar objects. Also, the proof of that CIRCUIT VALUE is P-complete results from the Cook-Levin problem, the same theorem that actually shows that SAT is NP-Complete, so I don't see a reason why this problem won't be P-Complete. From the other hand, it seems pretty easy to evaluate a Boolean formula in logarithmic space, so if this problem is indeed P-complete I think it would imply L = P which is unknown.

So I think I'm missing something.. any ideas people?

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this is apparently the same as the "boolean formula value problem" similar to the "boolean sentence value problem" (BSVP) proven to be in ALOGTIME by Buss-Cook-Gupta-Ramachandran. an improved algorithm and refs are given in Algorithms for Boolean Formula Evaluation and for Tree Contraction by Buss.

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In his 1987 paper "The Boolean formula value problem is in ALOGTIME", Buss showed that Boolean formula evaluation is in ALOGTIME (alternating logarithmic time), which is a uniform version of NC1 and so probably smaller than P. It is also ALOGTIME-complete under AC0 reductions.

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  • $\begingroup$ so does it mean that Boolean formula evaluation is not P-complete? $\endgroup$ – John Smith May 1 '13 at 17:23
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    $\begingroup$ We don't know that for sure, but that's probably correct. $\endgroup$ – Yuval Filmus May 1 '13 at 17:24

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