Description: The value of a state is nonnegative. (Contributed by NM, 24-Oct-1999) (Revised by Mario Carneiro, 23-Dec-2013) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | stge0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sticl | ||
2 | elicc01 | ||
3 | 2 | simp2bi | |
4 | 1 3 | syl6 |