:: BOOLE semantic presentation
theorem Th1: :: BOOLE:1
theorem Th2: :: BOOLE:2
theorem Th3: :: BOOLE:3
for b
1 being
set holds b
1 \ {} = b
1
theorem Th4: :: BOOLE:4
theorem Th5: :: BOOLE:5
theorem Th6: :: BOOLE:6
theorem Th7: :: BOOLE:7
for b
1, b
2 being
set holds
not ( b
1 in b
2 & b
2 is
empty )
theorem Th8: :: BOOLE:8