theorem Th43: :: MESFUN12:43

for X1, X2 being non empty set
for A, B being Subset of [:X1,X2:]
for p being set holds
( X-section ((A \ B),p) = (X-section (A,p)) \ (X-section (B,p)) & Y-section ((A \ B),p) = (Y-section (A,p)) \ (Y-section (B,p)) )