A1: union PA = Y by EQREL_1:def 4;
A2: for A being set st A in PA holds
( A <> {} & ( for B being set holds
( not B in PA or A = B or A misses B ) ) ) by EQREL_1:def 4;
defpred S₁[ set ] means $1 is_min_depend PA,PB;
consider X being set such that
A3: for d being set holds
( d in X iff ( d in bool Y & S₁[d] ) ) from XFAMILY:sch 1();
A4: for d being set holds
( d in X iff d is_min_depend PA,PB )

let d be set ; :: thesis:
for d being set st d is_min_depend PA,PB holds
d in bool Y

let d be set ; :: thesis:
assume d is_min_depend PA,PB ; :: thesis:
then d is_a_dependent_set_of PA ;
then ex A being set st
( A c= PA & A <> {} & d = union A ) ;
then d c= union PA by ZFMISC_1:77;
hence d in bool Y by A1; :: thesis:

end;

then ( d is_min_depend PA,PB implies ( d is_min_depend PA,PB & d in bool Y ) ) ;
hence ( d in X iff d is_min_depend PA,PB ) by A3; :: thesis:

end;

take X ; :: thesis:
A5: Y c= union X

let y be object ; :: according to TARSKI:def 3 :: thesis:
assume y in Y ; :: thesis:
then consider a being Subset of Y such that
A6: y in a and
A7: a is_min_depend PA,PB by Th11;
a in X by A4, A7;
hence y in union X by A6, TARSKI:def 4; :: thesis:

end;

union X c= Y

let y be object ; :: according to TARSKI:def 3 :: thesis:
assume y in union X ; :: thesis:
then consider a being set such that
A8: y in a and
A9: a in X by TARSKI:def 4;
a is_min_depend PA,PB by A4, A9;
then a is_a_dependent_set_of PA ;
then ex A being set st
( A c= PA & A <> {} & a = union A ) ;
then a c= Y by A1, ZFMISC_1:77;
hence y in Y by A8; :: thesis:

end;

then A10: union X = Y by A5, XBOOLE_0:def 10;
A11: for A being Subset of Y st A in X holds
( A <> {} & ( for B being Subset of Y holds
( not B in X or A = B or A misses B ) ) )

let A be Subset of Y; :: thesis:
assume A in X ; :: thesis:
then A12: A is_min_depend PA,PB by A4;
then A13: A is_a_dependent_set_of PA ;
A14: A is_a_dependent_set_of PB by A12;
consider Aa being set such that
A15: Aa c= PA and
A16: Aa <> {} and
A17: A = union Aa by A13;
consider aa being object such that
A18: aa in Aa by A16, XBOOLE_0:def 1;
A19: aa <> {} by A2, A15, A18;
reconsider aa = aa as set by TARSKI:1;
aa c= union Aa by A18, ZFMISC_1:74;
hence A <> {} by A17, A19; :: thesis:
let B be Subset of Y; :: thesis:
assume B in X ; :: thesis:
then A20: B is_min_depend PA,PB by A4;
then A21: ( B is_a_dependent_set_of PA & B is_a_dependent_set_of PB ) ;

assume A meets B ; :: thesis:
then A22: ( A /\ B is_a_dependent_set_of PA & A /\ B is_a_dependent_set_of PB ) by A13, A14, A21, Th9;
A /\ B c= A by XBOOLE_1:17;
then A23: A /\ B = A by A12, A22;
A24: A c= B by A23, XBOOLE_0:def 4;
A /\ B c= B by XBOOLE_1:17;
then A25: A /\ B = B by A20, A22;
B c= A by A25, XBOOLE_0:def 4;
hence A = B by A24, XBOOLE_0:def 10; :: thesis:

end;

hence ( A = B or A misses B ) ; :: thesis:

end;

let x be object ; :: according to TARSKI:def 3 :: thesis:
reconsider xx = x as set by TARSKI:1;
assume x in X ; :: thesis:
then xx is_min_depend PA,PB by A4;
then xx is_a_dependent_set_of PA ;
then ex a being set st
( a c= PA & a <> {} & x = union a ) ;
then xx c= Y by A1, ZFMISC_1:77;
hence x in bool Y ; :: thesis:

end;

then reconsider X = X as Subset-Family of Y ;
X is a_partition of Y by A10, A11, EQREL_1:def 4;
hence ( X is Element of bool (bool Y) & X is a_partition of Y & ( for d being set holds
( d in X iff d is_min_depend PA,PB ) ) ) by A4; :: thesis: