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| Mirrors > Home > MPE Home > Th. List > Mathboxes > df-sgrp2 | Structured version Visualization version GIF version | ||
| Description: A semigroup is a magma with an associative operation. Definition in section II.1 of [Bruck] p. 23, or of an "associative magma" in definition 5 of [BourbakiAlg1] p. 4, or of a semigroup in section 1.3 of [Hall] p. 7. (Contributed by AV, 6-Jan-2020.) | 
| Ref | Expression | 
|---|---|
| df-sgrp2 | ⊢ SGrpALT = {𝑔 ∈ MgmALT ∣ (+g‘𝑔) assLaw (Base‘𝑔)} | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | csgrp2 48138 | . 2 class SGrpALT | |
| 2 | vg | . . . . . 6 setvar 𝑔 | |
| 3 | 2 | cv 1538 | . . . . 5 class 𝑔 | 
| 4 | cplusg 17298 | . . . . 5 class +g | |
| 5 | 3, 4 | cfv 6560 | . . . 4 class (+g‘𝑔) | 
| 6 | cbs 17248 | . . . . 5 class Base | |
| 7 | 3, 6 | cfv 6560 | . . . 4 class (Base‘𝑔) | 
| 8 | casslaw 48105 | . . . 4 class assLaw | |
| 9 | 5, 7, 8 | wbr 5142 | . . 3 wff (+g‘𝑔) assLaw (Base‘𝑔) | 
| 10 | cmgm2 48136 | . . 3 class MgmALT | |
| 11 | 9, 2, 10 | crab 3435 | . 2 class {𝑔 ∈ MgmALT ∣ (+g‘𝑔) assLaw (Base‘𝑔)} | 
| 12 | 1, 11 | wceq 1539 | 1 wff SGrpALT = {𝑔 ∈ MgmALT ∣ (+g‘𝑔) assLaw (Base‘𝑔)} | 
| Colors of variables: wff setvar class | 
| This definition is referenced by: issgrpALT 48146 | 
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