Description: Alternate proof of 2cn . Shorter but uses more axioms. Similar proofs are possible for 3cn , ... , 9cn . (Contributed by NM, 30-Jul-2004) (Proof modification is discouraged.) (New usage is discouraged.)
Ref | Expression | ||
---|---|---|---|
Assertion | 2cnALT | |- 2 e. CC |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 2re | |- 2 e. RR |
|
2 | 1 | recni | |- 2 e. CC |