Description: Define the set of square positive integers. (Contributed by Stefan O'Rear, 18-Sep-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | df-squarenn | |- []NN = { x e. NN | ( sqrt ` x ) e. QQ } |
Step | Hyp | Ref | Expression |
---|---|---|---|
0 | csquarenn | |- []NN |
|
1 | vx | |- x |
|
2 | cn | |- NN |
|
3 | csqrt | |- sqrt |
|
4 | 1 | cv | |- x |
5 | 4 3 | cfv | |- ( sqrt ` x ) |
6 | cq | ||
7 | 5 6 | wcel | |- ( sqrt ` x ) e. QQ |
8 | 7 1 2 | crab | |- { x e. NN | ( sqrt ` x ) e. QQ } |
9 | 0 8 | wceq | |- []NN = { x e. NN | ( sqrt ` x ) e. QQ } |