Talk:True quantified Boolean formula
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The example given at the beginning is somewhat unsuitable because the boolean part is already valid, and therfore true for any combination of Quantifiers 134.2.102.191 (talk) 14:29, 6 April 2009 (UTC)
and
It would be nice to have a comparison with and ( and , respectively) too. 129.240.71.6 (talk) 16:40, 28 March 2011 (UTC)
Miscellany addition
Quantified monotone boolean formulas are linearly decidable. Just plug in True for existentially quantified variables, and False for universally quantified variables, then evaluate.
Additionally, the number of valid quantifications of a boolean formula is equal to the number of satisfying assignments of the boolean formula. (i.e. #P=#PSpace). 24.33.70.144 (talk) 21:24, 1 March 2014 (UTC)Daniel Pehoushek
This article is not self-contained.
There is no mention of MA (Merlyn/Arthur) before the mention in the paragraph starting:
Provided that MA ⊊ PSPACE, ...
What means that?
I am not expert in Complexity Theory, please can someone rewrite this article in a self contained style. State what is the problem, what has been discovered to build QBF and in what extent can them be solved in practice. What problems remain to be solved. And a schema to guide the reader into this subject.
SPACE complexity
Stating "Thus, this algorithm uses O(n + log n) = O(n) space. This makes the TQBF language part of the PSPACE complexity class." is misleading or even wrong. The algorithm actually uses polynomial space (in the number of variables). If it was O(n), PSPACE would be equal to linear space LIN, since the problem is complete for PSPACE. This is obviously not true... The problem most likely occurred since the problem can be solved in non-deterministic linear space (by just running the given algorithm non-deterministically), so it is in non-deterministic linear space NLIN.