let A, B be Relation of M; :: thesis: ( ( for x, y being Element of M holds
( [x,y] in A iff x,y are_in_tolerance_wrt a ) ) & ( for x, y being Element of M holds
( [x,y] in B iff x,y are_in_tolerance_wrt a ) ) implies A = B )

assume that
A2: for x, y being Element of M holds
( [x,y] in A iff x,y are_in_tolerance_wrt a ) and
A3: for x, y being Element of M holds
( [x,y] in B iff x,y are_in_tolerance_wrt a ) ; :: thesis: A = B
A4: for c, d being object st [c,d] in B holds
[c,d] in A
proof
let c, d be object ; :: thesis: ( [c,d] in B implies [c,d] in A )
assume A5: [c,d] in B ; :: thesis: [c,d] in A
then reconsider c1 = c, d1 = d as Element of M by ZFMISC_1:87;
c1,d1 are_in_tolerance_wrt a by A3, A5;
hence [c,d] in A by A2; :: thesis: verum
end;
for c, d being object st [c,d] in A holds
[c,d] in B
proof
let c, d be object ; :: thesis: ( [c,d] in A implies [c,d] in B )
assume A6: [c,d] in A ; :: thesis: [c,d] in B
then reconsider c1 = c, d1 = d as Element of M by ZFMISC_1:87;
c1,d1 are_in_tolerance_wrt a by A2, A6;
hence [c,d] in B by A3; :: thesis: verum
end;
hence A = B by ; :: thesis: verum