▁of ▁job ▁ ▁on ▁machine ▁, ▁there ▁is ▁a ▁transport ation ▁delay ▁of ▁at ▁least ▁ ▁units . ▁▁▁▁ ▁Machine ▁pair ▁dependent ▁transport ation ▁delay . ▁Between ▁the ▁completion ▁of ▁operation ▁ ▁of ▁job ▁ ▁on ▁machine ▁ ▁and ▁the ▁start ▁of ▁operation ▁ ▁of ▁job ▁ ▁on ▁machine ▁, ▁there ▁is ▁a ▁transport ation ▁delay ▁of ▁at ▁least ▁ ▁units . ▁▁▁▁ ▁Job ▁dependent ▁transport ation ▁delay . ▁Between ▁the ▁completion ▁of ▁operation ▁ ▁of ▁job ▁ ▁on ▁machine ▁ ▁and ▁the ▁start ▁of ▁operation ▁ ▁of ▁job ▁ ▁on ▁machine ▁, ▁there ▁is ▁a ▁transport ation ▁delay ▁of ▁at ▁least ▁ ▁units . ▁ ▁Vari ous ▁constraints ▁▁▁ ▁r c rc ▁ ▁Rec ir cul ation , ▁also ▁called ▁F lex ible ▁job ▁shop . ▁The ▁promise ▁on ▁ ▁is ▁lifted ▁and ▁for ▁some ▁pairs ▁ ▁we ▁might ▁have ▁. ▁ ▁no - wait ▁ ▁The ▁operation ▁must ▁start ▁exactly ▁when ▁operation ▁ ▁comple tes . ▁ ▁Sometimes ▁also ▁denoted ▁as ▁' n wt '. ▁ ▁no - id le ▁ ▁No ▁machine ▁is ▁ever ▁idle ▁between ▁two ▁execution s . ▁▁▁ ▁Mult ip ro cess or ▁tasks ▁on ▁identical ▁parallel ▁machines . ▁The ▁execution ▁of ▁job ▁ ▁is ▁done ▁simultaneously ▁on ▁parallel ▁machines . ▁▁▁ ▁Mult ip ro cess or ▁tasks . ▁Every ▁job ▁is ▁given ▁with ▁a ▁set ▁of ▁machines ▁, ▁and ▁needs ▁simultaneously ▁all ▁these ▁machines ▁for ▁execution . ▁Sometimes ▁also ▁denoted ▁by ▁' MP T '. ▁▁▁ ▁Mult ip ur pose ▁machines . ▁Every ▁job ▁needs ▁to