Description: gcdOLD ( A , B ) is the largest positive integer that evenly divides both A and B . (Contributed by Jeff Hoffman, 17-Jun-2008) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-gcdOLD | |- gcdOLD ( A , B ) = sup ( { x e. NN | ( ( A / x ) e. NN /\ ( B / x ) e. NN ) } , NN , < ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | cA | |- A | |
| 1 | cB | |- B | |
| 2 | 0 1 | cgcdOLD | |- gcdOLD ( A , B ) | 
| 3 | vx | |- x | |
| 4 | cn | |- NN | |
| 5 | cdiv | |- / | |
| 6 | 3 | cv | |- x | 
| 7 | 0 6 5 | co | |- ( A / x ) | 
| 8 | 7 4 | wcel | |- ( A / x ) e. NN | 
| 9 | 1 6 5 | co | |- ( B / x ) | 
| 10 | 9 4 | wcel | |- ( B / x ) e. NN | 
| 11 | 8 10 | wa | |- ( ( A / x ) e. NN /\ ( B / x ) e. NN ) | 
| 12 | 11 3 4 | crab |  |-  { x e. NN | ( ( A / x ) e. NN /\ ( B / x ) e. NN ) } | 
| 13 | clt | |- < | |
| 14 | 12 4 13 | csup |  |-  sup ( { x e. NN | ( ( A / x ) e. NN /\ ( B / x ) e. NN ) } , NN , < ) | 
| 15 | 2 14 | wceq |  |-  gcdOLD ( A , B ) = sup ( { x e. NN | ( ( A / x ) e. NN /\ ( B / x ) e. NN ) } , NN , < ) |