Description: The union of two numerable sets is numerable. (Contributed by Mario Carneiro, 29-Apr-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | unnum | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | djunum | |
|
2 | undjudom | |
|
3 | numdom | |
|
4 | 1 2 3 | syl2anc | |