Description: Even the monoid of endofunctions on the empty set is actually a monoid. (Contributed by AV, 31-Jan-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | efmnd0nmnd | ⊢ ( EndoFMnd ‘ ∅ ) ∈ Mnd |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ex | ⊢ ∅ ∈ V | |
2 | eqid | ⊢ ( EndoFMnd ‘ ∅ ) = ( EndoFMnd ‘ ∅ ) | |
3 | 2 | efmndmnd | ⊢ ( ∅ ∈ V → ( EndoFMnd ‘ ∅ ) ∈ Mnd ) |
4 | 1 3 | ax-mp | ⊢ ( EndoFMnd ‘ ∅ ) ∈ Mnd |