theorem Th19: :: MSSUBLAT:19

for MS being non void 1 -element segmental ManySortedSign
for A being non-empty MSAlgebra over MS
for B being non-empty MSSubAlgebra of A
for S being non empty Subset of (1-Alg A) st S = the carrier of (1-Alg B) holds
the charact of (1-Alg B) = Opers ((1-Alg A),S)