Answered>Order 3773

  1. Let’sconsideraspecialcaseofQuantified3-SATinwhichtheunderlying Boolean formula has no negated variables. Specifically, let (x1, . . . , xn) be a Boolean formula of the form
  2. C1 ? C2 ? . . . ? Ck ,
  3. where each Ci is a disjunction of three terms. We say is monotone if each term in each clause consists of a nonnegated variable—that is, each term is equal to xi, for some i, rather than xi.
  4. We define Monotone QSAT to be the decision problem
  5. ?x1?x2 . . . ?xn?2?xn?1?xn (x1, . . . , xn)? where the formula is monotone.
  6. Do one of the following two things: (a) prove that Monotone QSAT is PSPACE-complete; or (b) give an algorithm to solve arbitrary instances of Monotone QSAT that runs in time polynomial in n. (Note that in (b), the goal is polynomial time, not just polynomial space.) 
 
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