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Description: Submonoids contain zero. (Contributed by Mario Carneiro, 7-Mar-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | subm0cl.z | ||
| Assertion | subm0cl |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | subm0cl.z | ||
| 2 | submrcl | ||
| 3 | eqid | ||
| 4 | eqid | ||
| 5 | 3 1 4 | issubm2 | |
| 6 | 2 5 | syl | |
| 7 | 6 | ibi | |
| 8 | 7 | simp2d |