PSPACE-hard

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In computational complexity theory, a decision problem p is said to be PSPACE-hard if, given any decision problem q in PSPACE, q can be reduced to p in polynomial time. PSPACE-hardness is distinguished from PSPACE-completeness by the fact that PSPACE-hardness does not require the problem to be in PSPACE. For example, the halting problem is PSPACE-hard, but not PSPACE-complete.

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