for i, j being Nat st [i,j] in Indices (M @ ) holds
(M @ ) * i,j > 0
proof
let i,
j be
Nat;
:: thesis: ( [i,j] in Indices (M @ ) implies (M @ ) * i,j > 0 )
assume
[i,j] in Indices (M @ )
;
:: thesis: (M @ ) * i,j > 0
then A1:
[j,i] in Indices M
by MATRIX_1:def 7;
then
(M @ ) * i,
j = M * j,
i
by MATRIX_1:def 7;
hence
(M @ ) * i,
j > 0
by A1, Def1;
:: thesis: verum
end;
hence
M @ is Positive
by Def1; :: thesis: verum