A4:
dom (abs f) = dom f
by VALUED_1:def 11;

len f = n by CARD_1:def 7;

hence len (abs f) = n by A4, FINSEQ_3:29; :: according to CARD_1:def 7 :: thesis: verum

len f = n by CARD_1:def 7;

hence len (abs f) = n by A4, FINSEQ_3:29; :: according to CARD_1:def 7 :: thesis: verum