theorem Th44: :: MESFUN12:44

for X1, X2 being non empty set
for x being Element of X1
for y being Element of X2
for f1, f2 being PartFunc of [:X1,X2:],ExtREAL holds
( ProjPMap1 ((f1 + f2),x) = (ProjPMap1 (f1,x)) + (ProjPMap1 (f2,x)) & ProjPMap1 ((f1 - f2),x) = (ProjPMap1 (f1,x)) - (ProjPMap1 (f2,x)) & ProjPMap2 ((f1 + f2),y) = (ProjPMap2 (f1,y)) + (ProjPMap2 (f2,y)) & ProjPMap2 ((f1 - f2),y) = (ProjPMap2 (f1,y)) - (ProjPMap2 (f2,y)) )