# Revision history [back]

### Evaluation of logical compound expressions

sage: foo=sin(x) > 0 ; foo
sin(x) > 0
sage: bar=cos(x)>0 ; bar
cos(x) > 0


I do not understand this :

sage: foo and bar
sin(x) > 0
sage: foo or bar
cos(x) > 0


As long as x has no value, these expressions can't be evaluated or simplified. Could some kind soul enlighten my confused mind ?