# Truth value of an expression (Boolean Polynomials)

I need to find the truth value of an expression. Consider this:

```
sage: R = BooleanPolynomialRing( 2, \
['s%d'%(i) for i in range (2)])
sage: expr = R('s0') + R('s0')*R('s1')
```

Now I need `expr`

is to be evaluated; given, say, both `s0`

and `s1`

are `True`

. How can we do that?