Description: A monoid is a semigroup with an identity element. (Contributed by FL, 2-Nov-2009) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-mndo | ⊢ MndOp = ( SemiGrp ∩ ExId ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 0 | cmndo | ⊢ MndOp | |
| 1 | csem | ⊢ SemiGrp | |
| 2 | cexid | ⊢ ExId | |
| 3 | 1 2 | cin | ⊢ ( SemiGrp ∩ ExId ) | 
| 4 | 0 3 | wceq | ⊢ MndOp = ( SemiGrp ∩ ExId ) |