ien ▁N ury ▁- ▁designer : ▁Th ier ry ▁Robin ▁- ▁color : ▁Lor ien ▁A ure y re ▁ ▁Fun éra illes , ▁D arg aud , ▁ ▁( ), ▁May ▁ 2 0 1 2 writer : ▁Fab ien ▁N ury ▁- ▁designer : ▁Th ier ry ▁Robin ▁- ▁Color ▁: ▁Lor ien ▁A ure y re ▁and ▁Th ier ry ▁Robin ▁ ▁References ▁▁ ▁Category : F rench ▁com ic ▁stri ps ▁Category : 2 0 1 0 ▁com ics ▁deb uts ▁Category : 2 0 1 2 ▁com ics ▁end ings ▁Category : Com ics ▁set ▁in ▁the ▁ 1 9 5 0 s ▁Category : Com ics ▁set ▁in ▁Russia ▁Category : F rench ▁com ics ▁adapted ▁into ▁films ▁Category : H istor ical ▁com ics ▁Category : S at ir ical ▁com ics ▁Category : C ult ural ▁dep ict ions ▁of ▁Joseph ▁St alin <0x0A> </s> ▁In ▁mathematics , ▁an ▁R - function , ▁or ▁R v ache v ▁function , ▁is ▁a ▁real - valu ed ▁function ▁whose ▁sign ▁does ▁not ▁change ▁if ▁none ▁of ▁the ▁signs ▁of ▁its ▁arguments ▁change ; ▁that ▁is , ▁its ▁sign ▁is ▁determined ▁sole ly ▁by ▁the ▁signs ▁of ▁its ▁arguments . ▁ ▁Inter pre ting ▁positive ▁values ▁as ▁true ▁and ▁negative ▁values ▁as ▁false , ▁an ▁R - function ▁is ▁transformed ▁into ▁a ▁" comp an ion " ▁Boolean ▁function ▁( the ▁two ▁functions ▁are ▁called ▁friends ). ▁For ▁instance , ▁the ▁R - function ▁ ƒ (