Class Description

UL: Unambiguous L

Has the same relation to L as UP does to P.

The problem of reachability in directed planar graphs lies in UL [SES05].

If UL = NL, then FNL is contained in #L [AJ93].

Linked From

FNL: Function NL

Has the same relation to NL as FNP does to NP.

Defined by [AJ93], who also showed that if NL = UL, then FNL is contained in #L.

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SPL: Stoic PL

Has the same relation to PL as SPP does to PP.

Contains the maximum matching and perfect matching problems under a pseudorandom assumption [ARZ99].

Contains UL.

Contained in C=L and ModkL.

Equals the set of problems low for GapL.

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UL/poly: Nonuniform UL

Has the same relation to UL as P/poly does to P.

Equals NL/poly [RA00]. (A corollary is that UL/poly is closed under complement).

Note that in UL/poly, the witness must be unique even for bad advice. UL/mpoly (as in BQP/mpoly) is a more natural definition, but this is a moot distinction here because [RA00] show that they both equal NL/poly.

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