▁death s ▁Category : De put ies ▁to ▁the ▁French ▁National ▁Convention ▁Category : F rench ▁min eral og ists ▁Category : F rench ▁natural ists ▁Category : Cor respond ing ▁M embers ▁of ▁the ▁St ▁Petersburg ▁Academy ▁of ▁Sciences ▁Category : Pe ople ▁from ▁Lyon <0x0A> </s> ▁This ▁is ▁a ▁list ▁of ▁complexity ▁classes ▁in ▁computational ▁complexity ▁theory . ▁For ▁other ▁computational ▁and ▁complexity ▁subjects , ▁see ▁list ▁of ▁comput ability ▁and ▁complexity ▁topics . ▁ ▁Many ▁of ▁these ▁classes ▁have ▁a ▁' co ' ▁partner ▁which ▁consists ▁of ▁the ▁comple ments ▁of ▁all ▁languages ▁in ▁the ▁original ▁class . ▁ ▁For ▁example ▁if ▁a ▁language ▁L ▁is ▁in ▁N P ▁then ▁the ▁complement ▁of ▁L ▁is ▁in ▁co - NP . ▁ ▁( This ▁does ▁not ▁mean ▁that ▁the ▁complement ▁of ▁N P ▁is ▁co - NP — there ▁are ▁languages ▁which ▁are ▁known ▁to ▁be ▁in ▁both , ▁and ▁other ▁languages ▁which ▁are ▁known ▁to ▁be ▁in ▁neither .) ▁ ▁" The ▁hard est ▁problems " ▁of ▁a ▁class ▁refer ▁to ▁problems ▁which ▁belong ▁to ▁the ▁class ▁such ▁that ▁every ▁other ▁problem ▁of ▁that ▁class ▁can ▁be ▁reduced ▁to ▁it . ▁Furthermore , ▁the ▁reduction ▁is ▁also ▁a ▁problem ▁of ▁the ▁given ▁class , ▁or ▁its ▁subset . ▁ ▁References ▁ ▁External ▁links ▁Complex ity ▁Z oo ▁- ▁list ▁of ▁over ▁ 5 0 0 ▁complexity ▁classes ▁and ▁their ▁properties ▁ ▁* ▁Complex ity ▁classes <0x0A> </s> ▁Go ▁With ▁the ▁Flow ▁is ▁an ▁album ▁by ▁American ▁viol in ist ▁and