let I be non empty set ; :: thesis: for A, B being non trivial-yielding Segre-like ManySortedSet of st 2 c= card ((product A) /\ (product B)) holds
( indx A = indx B & ( for i being set st i <> indx A holds
A . i = B . i ) )
let A, B be non trivial-yielding Segre-like ManySortedSet of ; :: thesis: ( 2 c= card ((product A) /\ (product B)) implies ( indx A = indx B & ( for i being set st i <> indx A holds
A . i = B . i ) ) )
assume
2 c= card ((product A) /\ (product B))
; :: thesis: ( indx A = indx B & ( for i being set st i <> indx A holds
A . i = B . i ) )
then consider a, b being set such that
A1:
( a in (product A) /\ (product B) & b in (product A) /\ (product B) & a <> b )
by Th2;
a in product A
by A1, XBOOLE_0:def 4;
then consider a1 being Function such that
A2:
( a1 = a & dom a1 = dom A & ( for o being set st o in dom A holds
a1 . o in A . o ) )
by CARD_3:def 5;
A3:
a in product B
by A1, XBOOLE_0:def 4;
b in product A
by A1, XBOOLE_0:def 4;
then consider b1 being Function such that
A4:
( b1 = b & dom b1 = dom A & ( for o being set st o in dom A holds
b1 . o in A . o ) )
by CARD_3:def 5;
A5:
b in product B
by A1, XBOOLE_0:def 4;
consider o being set such that
A6:
( o in dom A & a1 . o <> b1 . o )
by A1, A2, A4, FUNCT_1:9;
reconsider o = o as Element of I by A6, PARTFUN1:def 4;
( a1 . o in A . o & b1 . o in A . o )
by A2, A4, A6;
then
2 c= card (A . o)
by A6, Th2;
then
not A . o is trivial
by Th4;
then A7:
o = indx A
by Def21;
dom B = I
by PARTFUN1:def 4;
then
( a1 . o in B . o & b1 . o in B . o )
by A2, A3, A4, A5, CARD_3:18;
then
2 c= card (B . o)
by A6, Th2;
then A8:
not B . o is trivial
by Th4;
then A9:
o = indx B
by Def21;
thus
indx A = indx B
by A7, A8, Def21; :: thesis: for i being set st i <> indx A holds
A . i = B . i
let i be set ; :: thesis: ( i <> indx A implies A . i = B . i )
assume A10:
i <> indx A
; :: thesis: A . i = B . i
per cases
( i in I or not i in I )
;
suppose A11:
i in I
;
:: thesis: A . i = B . ithen A12:
( not
A . i is
empty &
A . i is
trivial & not
B . i is
empty &
B . i is
trivial )
by A7, A9, A10, Th12;
then consider x being
set such that A13:
A . i = {x}
by REALSET1:def 4;
consider y being
set such that A14:
B . i = {y}
by A12, REALSET1:def 4;
dom A = I
by PARTFUN1:def 4;
then
a1 . i in A . i
by A2, A11;
then A15:
a1 . i = x
by A13, TARSKI:def 1;
dom B = I
by PARTFUN1:def 4;
then
a1 . i in B . i
by A2, A3, A11, CARD_3:18;
hence
A . i = B . i
by A13, A14, A15, TARSKI:def 1;
:: thesis: verum end; end;