▁instance ▁of ▁. ▁ ▁Specifically , ▁as ▁shown ▁above , ▁info - g ap ' s ▁robust ness ▁model ▁is ▁an ▁instance ▁of ▁the ▁generic ▁maxim in ▁model ▁specified ▁by ▁the ▁following ▁construct s : ▁▁▁▁ ▁Furthermore , ▁those ▁object ing ▁to ▁the ▁use ▁of ▁the ▁term ▁ ▁instance ▁of ▁  ▁ ▁should ▁note ▁that ▁the ▁Max imin ▁model ▁form ulated ▁above ▁has ▁an ▁equivalent ▁so ▁called ▁ ▁Mathemat ical ▁Program ming ▁  ▁( MP ) ▁form ulation ▁der iving ▁from ▁the ▁fact ▁that ▁▁▁▁ ▁where ▁ ▁denotes ▁the ▁real ▁line . ▁ ▁So ▁here ▁are ▁side ▁by ▁side ▁info - g ap ' s ▁robust ness ▁model ▁and ▁the ▁two ▁equivalent ▁form ulations ▁of ▁the ▁generic ▁maxim in ▁parad ig m : ▁▁▁▁ ▁Note ▁that ▁the ▁equivalence ▁between ▁these ▁three ▁representations ▁of ▁the ▁same ▁decision - making ▁situation ▁makes ▁no ▁use ▁of ▁dummy ▁variables . ▁It ▁is ▁based ▁on ▁the ▁equivalence ▁▁▁▁ ▁der iving ▁directly ▁from ▁the ▁definition ▁of ▁the ▁characteristic ▁function ▁. ▁ ▁Clear ly ▁then , ▁info - g ap ' s ▁robust ness ▁model ▁is ▁an ▁instance ▁of ▁the ▁generic ▁maxim in ▁model . ▁ ▁Similarly , ▁for ▁info - g ap ' s ▁opportun eness ▁model ▁we ▁have ▁▁▁▁ ▁Again , ▁it ▁should ▁be ▁str essed ▁that ▁the ▁equivalence ▁between ▁these ▁three ▁representations ▁of ▁the ▁same ▁decision - making ▁situation ▁makes ▁no ▁use ▁of ▁dummy ▁variables . ▁It ▁is ▁based ▁on ▁the ▁equivalence ▁▁▁▁ ▁der iving ▁directly ▁from ▁the ▁definition ▁of ▁the ▁characteristic ▁function ▁. ▁ ▁Thus ,