▁and ▁Mar vin ▁Stern ▁in ▁ 1 9 5 0 s . ▁ ▁A ▁procedure ▁for ▁three ▁partners ▁and ▁general ▁pieces ▁was ▁found ▁in ▁ 1 9 6 0 . ▁A ▁procedure ▁for ▁three ▁partners ▁and ▁connected ▁pieces ▁was ▁found ▁only ▁in ▁ 1 9 8 0 . ▁ ▁En vy - free ▁division ▁for ▁four ▁or ▁more ▁partners ▁has ▁been ▁an ▁open ▁problem ▁until ▁the ▁ 1 9 9 0 s , ▁when ▁three ▁procedures ▁for ▁general ▁pieces ▁and ▁a ▁procedure ▁for ▁connected ▁pieces ▁have ▁been ▁published . ▁All ▁these ▁procedures ▁are ▁un bounded ▁- ▁they ▁may ▁require ▁a ▁number ▁of ▁steps ▁which ▁is ▁not ▁bounded ▁in ▁advance . ▁The ▁procedure ▁for ▁connected ▁pieces ▁may ▁even ▁require ▁an ▁infinite ▁number ▁of ▁steps . ▁ ▁Two ▁lower ▁bounds ▁on ▁the ▁run - time ▁complexity ▁of ▁env y - f reen ess ▁have ▁been ▁published ▁in ▁the ▁ 2 0 0 0 s . ▁▁ ▁For ▁general ▁pieces , ▁the ▁lower ▁bound ▁is ▁ Ω ( n 2 ). ▁▁ ▁For ▁connected ▁pieces ▁the ▁lower ▁bound ▁is ▁infinity ▁– ▁there ▁is ▁prov ably ▁no ▁finite ▁protocol ▁for ▁three ▁or ▁more ▁partners . ▁ ▁In ▁the ▁ 2 0 1 0 s , ▁several ▁approximation ▁procedures ▁and ▁procedures ▁for ▁special ▁cases ▁have ▁been ▁published . ▁The ▁question ▁whether ▁bounded - time ▁procedures ▁exist ▁for ▁the ▁case ▁of ▁general ▁pieces ▁had ▁remained ▁open ▁for ▁a ▁long ▁time . ▁The ▁problem ▁was ▁finally ▁solved ▁in ▁ 2 0 1 6 . ▁Har is ▁Az iz ▁and ▁Simon