:: deftheorem Def1 defines subsymmetric MATRIX17:def 1 :
for K being Field
for n being Nat
for M being Matrix of n,K holds
( M is subsymmetric iff for i, j, k, l being Nat st [i,j] in Indices M & k = (n + 1) - j & l = (n + 1) - i holds
M * (i,j) = M * (k,l) );