Description: The group addition operation is a function. (Contributed by Mario Carneiro, 14-Aug-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | grpplusf.1 | ||
| grpplusf.2 | |||
| Assertion | grpplusf | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | grpplusf.1 | ||
| 2 | grpplusf.2 | ||
| 3 | grpmnd | ||
| 4 | 1 2 | mndplusf | |
| 5 | 3 4 | syl |