“…sat(a', M') iemainIEs(a'): sat(ie, M'), applying Definition 2 over a' [2] iemainIEs(a): sat(ie, M), since ie s is not added as main IE [3] sat(a, M), applying Definition 2 over a [4] sat(b, M), applying the IH [5] iemainIEs(b): sat(ie, M), applying Definition 2 over b [6] iemainIEs(b): sat(ie, M'), since b is the same in M and M' [7] sat(b, M'), applying Definition 2 over b CASE 2. Main IEs addition.…”