Description: A monoid is a magma with an identity element. (Contributed by FL, 18-Feb-2010) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | mndomgmid | ⊢ ( 𝐺 ∈ MndOp → 𝐺 ∈ ( Magma ∩ ExId ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | mndoismgmOLD | ⊢ ( 𝐺 ∈ MndOp → 𝐺 ∈ Magma ) | |
| 2 | mndoisexid | ⊢ ( 𝐺 ∈ MndOp → 𝐺 ∈ ExId ) | |
| 3 | 1 2 | elind | ⊢ ( 𝐺 ∈ MndOp → 𝐺 ∈ ( Magma ∩ ExId ) ) |