| Step | Hyp | Ref
 | Expression | 
| 1 |   | basfn 12736 | 
. . . 4
⊢ Base Fn
V | 
| 2 |   | vex 2766 | 
. . . 4
⊢ 𝑔 ∈ V | 
| 3 |   | funfvex 5575 | 
. . . . 5
⊢ ((Fun
Base ∧ 𝑔 ∈ dom
Base) → (Base‘𝑔)
∈ V) | 
| 4 | 3 | funfni 5358 | 
. . . 4
⊢ ((Base Fn
V ∧ 𝑔 ∈ V) →
(Base‘𝑔) ∈
V) | 
| 5 | 1, 2, 4 | mp2an 426 | 
. . 3
⊢
(Base‘𝑔)
∈ V | 
| 6 |   | plusgslid 12790 | 
. . . . 5
⊢
(+g = Slot (+g‘ndx) ∧
(+g‘ndx) ∈ ℕ) | 
| 7 | 6 | slotex 12705 | 
. . . 4
⊢ (𝑔 ∈ V →
(+g‘𝑔)
∈ V) | 
| 8 | 7 | elv 2767 | 
. . 3
⊢
(+g‘𝑔) ∈ V | 
| 9 |   | fveq2 5558 | 
. . . . . . 7
⊢ (𝑔 = 𝐺 → (Base‘𝑔) = (Base‘𝐺)) | 
| 10 |   | ismnddef.b | 
. . . . . . 7
⊢ 𝐵 = (Base‘𝐺) | 
| 11 | 9, 10 | eqtr4di 2247 | 
. . . . . 6
⊢ (𝑔 = 𝐺 → (Base‘𝑔) = 𝐵) | 
| 12 | 11 | eqeq2d 2208 | 
. . . . 5
⊢ (𝑔 = 𝐺 → (𝑏 = (Base‘𝑔) ↔ 𝑏 = 𝐵)) | 
| 13 |   | fveq2 5558 | 
. . . . . . 7
⊢ (𝑔 = 𝐺 → (+g‘𝑔) = (+g‘𝐺)) | 
| 14 |   | ismnddef.p | 
. . . . . . 7
⊢  + =
(+g‘𝐺) | 
| 15 | 13, 14 | eqtr4di 2247 | 
. . . . . 6
⊢ (𝑔 = 𝐺 → (+g‘𝑔) = + ) | 
| 16 | 15 | eqeq2d 2208 | 
. . . . 5
⊢ (𝑔 = 𝐺 → (𝑝 = (+g‘𝑔) ↔ 𝑝 = + )) | 
| 17 | 12, 16 | anbi12d 473 | 
. . . 4
⊢ (𝑔 = 𝐺 → ((𝑏 = (Base‘𝑔) ∧ 𝑝 = (+g‘𝑔)) ↔ (𝑏 = 𝐵 ∧ 𝑝 = + ))) | 
| 18 |   | simpl 109 | 
. . . . 5
⊢ ((𝑏 = 𝐵 ∧ 𝑝 = + ) → 𝑏 = 𝐵) | 
| 19 |   | oveq 5928 | 
. . . . . . . . 9
⊢ (𝑝 = + → (𝑒𝑝𝑎) = (𝑒 + 𝑎)) | 
| 20 | 19 | eqeq1d 2205 | 
. . . . . . . 8
⊢ (𝑝 = + → ((𝑒𝑝𝑎) = 𝑎 ↔ (𝑒 + 𝑎) = 𝑎)) | 
| 21 |   | oveq 5928 | 
. . . . . . . . 9
⊢ (𝑝 = + → (𝑎𝑝𝑒) = (𝑎 + 𝑒)) | 
| 22 | 21 | eqeq1d 2205 | 
. . . . . . . 8
⊢ (𝑝 = + → ((𝑎𝑝𝑒) = 𝑎 ↔ (𝑎 + 𝑒) = 𝑎)) | 
| 23 | 20, 22 | anbi12d 473 | 
. . . . . . 7
⊢ (𝑝 = + → (((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) | 
| 24 | 23 | adantl 277 | 
. . . . . 6
⊢ ((𝑏 = 𝐵 ∧ 𝑝 = + ) → (((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) | 
| 25 | 18, 24 | raleqbidv 2709 | 
. . . . 5
⊢ ((𝑏 = 𝐵 ∧ 𝑝 = + ) → (∀𝑎 ∈ 𝑏 ((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ∀𝑎 ∈ 𝐵 ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) | 
| 26 | 18, 25 | rexeqbidv 2710 | 
. . . 4
⊢ ((𝑏 = 𝐵 ∧ 𝑝 = + ) → (∃𝑒 ∈ 𝑏 ∀𝑎 ∈ 𝑏 ((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ∃𝑒 ∈ 𝐵 ∀𝑎 ∈ 𝐵 ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) | 
| 27 | 17, 26 | biimtrdi 163 | 
. . 3
⊢ (𝑔 = 𝐺 → ((𝑏 = (Base‘𝑔) ∧ 𝑝 = (+g‘𝑔)) → (∃𝑒 ∈ 𝑏 ∀𝑎 ∈ 𝑏 ((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ∃𝑒 ∈ 𝐵 ∀𝑎 ∈ 𝐵 ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎)))) | 
| 28 | 5, 8, 27 | sbc2iedv 3062 | 
. 2
⊢ (𝑔 = 𝐺 → ([(Base‘𝑔) / 𝑏][(+g‘𝑔) / 𝑝]∃𝑒 ∈ 𝑏 ∀𝑎 ∈ 𝑏 ((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎) ↔ ∃𝑒 ∈ 𝐵 ∀𝑎 ∈ 𝐵 ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) | 
| 29 |   | df-mnd 13058 | 
. 2
⊢ Mnd =
{𝑔 ∈ Smgrp ∣
[(Base‘𝑔) /
𝑏][(+g‘𝑔) / 𝑝]∃𝑒 ∈ 𝑏 ∀𝑎 ∈ 𝑏 ((𝑒𝑝𝑎) = 𝑎 ∧ (𝑎𝑝𝑒) = 𝑎)} | 
| 30 | 28, 29 | elrab2 2923 | 
1
⊢ (𝐺 ∈ Mnd ↔ (𝐺 ∈ Smgrp ∧ ∃𝑒 ∈ 𝐵 ∀𝑎 ∈ 𝐵 ((𝑒 + 𝑎) = 𝑎 ∧ (𝑎 + 𝑒) = 𝑎))) |