| Step | Hyp | Ref
 | Expression | 
| 1 |   | df-ghm 13371 | 
. . 3
⊢  GrpHom =
(𝑠 ∈ Grp, 𝑡 ∈ Grp ↦ {𝑓 ∣
[(Base‘𝑠) /
𝑤](𝑓:𝑤⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))}) | 
| 2 | 1 | elmpocl 6118 | 
. 2
⊢ (𝐹 ∈ (𝑆 GrpHom 𝑇) → (𝑆 ∈ Grp ∧ 𝑇 ∈ Grp)) | 
| 3 |   | isghm.w | 
. . . . . . . 8
⊢ 𝑋 = (Base‘𝑆) | 
| 4 |   | basfn 12736 | 
. . . . . . . . 9
⊢ Base Fn
V | 
| 5 |   | elex 2774 | 
. . . . . . . . . 10
⊢ (𝑆 ∈ Grp → 𝑆 ∈ V) | 
| 6 | 5 | adantr 276 | 
. . . . . . . . 9
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → 𝑆 ∈ V) | 
| 7 |   | funfvex 5575 | 
. . . . . . . . . 10
⊢ ((Fun
Base ∧ 𝑆 ∈ dom
Base) → (Base‘𝑆)
∈ V) | 
| 8 | 7 | funfni 5358 | 
. . . . . . . . 9
⊢ ((Base Fn
V ∧ 𝑆 ∈ V) →
(Base‘𝑆) ∈
V) | 
| 9 | 4, 6, 8 | sylancr 414 | 
. . . . . . . 8
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) →
(Base‘𝑆) ∈
V) | 
| 10 | 3, 9 | eqeltrid 2283 | 
. . . . . . 7
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → 𝑋 ∈ V) | 
| 11 |   | isghm.x | 
. . . . . . . 8
⊢ 𝑌 = (Base‘𝑇) | 
| 12 |   | elex 2774 | 
. . . . . . . . . 10
⊢ (𝑇 ∈ Grp → 𝑇 ∈ V) | 
| 13 | 12 | adantl 277 | 
. . . . . . . . 9
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → 𝑇 ∈ V) | 
| 14 |   | funfvex 5575 | 
. . . . . . . . . 10
⊢ ((Fun
Base ∧ 𝑇 ∈ dom
Base) → (Base‘𝑇)
∈ V) | 
| 15 | 14 | funfni 5358 | 
. . . . . . . . 9
⊢ ((Base Fn
V ∧ 𝑇 ∈ V) →
(Base‘𝑇) ∈
V) | 
| 16 | 4, 13, 15 | sylancr 414 | 
. . . . . . . 8
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) →
(Base‘𝑇) ∈
V) | 
| 17 | 11, 16 | eqeltrid 2283 | 
. . . . . . 7
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → 𝑌 ∈ V) | 
| 18 |   | mapex 6713 | 
. . . . . . 7
⊢ ((𝑋 ∈ V ∧ 𝑌 ∈ V) → {𝑓 ∣ 𝑓:𝑋⟶𝑌} ∈ V) | 
| 19 | 10, 17, 18 | syl2anc 411 | 
. . . . . 6
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → {𝑓 ∣ 𝑓:𝑋⟶𝑌} ∈ V) | 
| 20 |   | simpl 109 | 
. . . . . . . 8
⊢ ((𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣))) → 𝑓:𝑋⟶𝑌) | 
| 21 | 20 | ss2abi 3255 | 
. . . . . . 7
⊢ {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ⊆ {𝑓 ∣ 𝑓:𝑋⟶𝑌} | 
| 22 | 21 | a1i 9 | 
. . . . . 6
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ⊆ {𝑓 ∣ 𝑓:𝑋⟶𝑌}) | 
| 23 | 19, 22 | ssexd 4173 | 
. . . . 5
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ∈ V) | 
| 24 |   | vex 2766 | 
. . . . . . . . . 10
⊢ 𝑠 ∈ V | 
| 25 |   | funfvex 5575 | 
. . . . . . . . . . 11
⊢ ((Fun
Base ∧ 𝑠 ∈ dom
Base) → (Base‘𝑠)
∈ V) | 
| 26 | 25 | funfni 5358 | 
. . . . . . . . . 10
⊢ ((Base Fn
V ∧ 𝑠 ∈ V) →
(Base‘𝑠) ∈
V) | 
| 27 | 4, 24, 26 | mp2an 426 | 
. . . . . . . . 9
⊢
(Base‘𝑠)
∈ V | 
| 28 |   | feq2 5391 | 
. . . . . . . . . 10
⊢ (𝑤 = (Base‘𝑠) → (𝑓:𝑤⟶(Base‘𝑡) ↔ 𝑓:(Base‘𝑠)⟶(Base‘𝑡))) | 
| 29 |   | raleq 2693 | 
. . . . . . . . . . 11
⊢ (𝑤 = (Base‘𝑠) → (∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ ∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 30 | 29 | raleqbi1dv 2705 | 
. . . . . . . . . 10
⊢ (𝑤 = (Base‘𝑠) → (∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ ∀𝑢 ∈ (Base‘𝑠)∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 31 | 28, 30 | anbi12d 473 | 
. . . . . . . . 9
⊢ (𝑤 = (Base‘𝑠) → ((𝑓:𝑤⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))) ↔ (𝑓:(Base‘𝑠)⟶(Base‘𝑡) ∧ ∀𝑢 ∈ (Base‘𝑠)∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))))) | 
| 32 | 27, 31 | sbcie 3024 | 
. . . . . . . 8
⊢
([(Base‘𝑠) / 𝑤](𝑓:𝑤⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))) ↔ (𝑓:(Base‘𝑠)⟶(Base‘𝑡) ∧ ∀𝑢 ∈ (Base‘𝑠)∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 33 |   | fveq2 5558 | 
. . . . . . . . . . 11
⊢ (𝑠 = 𝑆 → (Base‘𝑠) = (Base‘𝑆)) | 
| 34 | 33, 3 | eqtr4di 2247 | 
. . . . . . . . . 10
⊢ (𝑠 = 𝑆 → (Base‘𝑠) = 𝑋) | 
| 35 | 34 | feq2d 5395 | 
. . . . . . . . 9
⊢ (𝑠 = 𝑆 → (𝑓:(Base‘𝑠)⟶(Base‘𝑡) ↔ 𝑓:𝑋⟶(Base‘𝑡))) | 
| 36 |   | fveq2 5558 | 
. . . . . . . . . . . . . 14
⊢ (𝑠 = 𝑆 → (+g‘𝑠) = (+g‘𝑆)) | 
| 37 |   | isghm.a | 
. . . . . . . . . . . . . 14
⊢  + =
(+g‘𝑆) | 
| 38 | 36, 37 | eqtr4di 2247 | 
. . . . . . . . . . . . 13
⊢ (𝑠 = 𝑆 → (+g‘𝑠) = + ) | 
| 39 | 38 | oveqd 5939 | 
. . . . . . . . . . . 12
⊢ (𝑠 = 𝑆 → (𝑢(+g‘𝑠)𝑣) = (𝑢 + 𝑣)) | 
| 40 | 39 | fveqeq2d 5566 | 
. . . . . . . . . . 11
⊢ (𝑠 = 𝑆 → ((𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 41 | 34, 40 | raleqbidv 2709 | 
. . . . . . . . . 10
⊢ (𝑠 = 𝑆 → (∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 42 | 34, 41 | raleqbidv 2709 | 
. . . . . . . . 9
⊢ (𝑠 = 𝑆 → (∀𝑢 ∈ (Base‘𝑠)∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))) | 
| 43 | 35, 42 | anbi12d 473 | 
. . . . . . . 8
⊢ (𝑠 = 𝑆 → ((𝑓:(Base‘𝑠)⟶(Base‘𝑡) ∧ ∀𝑢 ∈ (Base‘𝑠)∀𝑣 ∈ (Base‘𝑠)(𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))) ↔ (𝑓:𝑋⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))))) | 
| 44 | 32, 43 | bitrid 192 | 
. . . . . . 7
⊢ (𝑠 = 𝑆 → ([(Base‘𝑠) / 𝑤](𝑓:𝑤⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))) ↔ (𝑓:𝑋⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))))) | 
| 45 | 44 | abbidv 2314 | 
. . . . . 6
⊢ (𝑠 = 𝑆 → {𝑓 ∣ [(Base‘𝑠) / 𝑤](𝑓:𝑤⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑤 ∀𝑣 ∈ 𝑤 (𝑓‘(𝑢(+g‘𝑠)𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))} = {𝑓 ∣ (𝑓:𝑋⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))}) | 
| 46 |   | fveq2 5558 | 
. . . . . . . . . 10
⊢ (𝑡 = 𝑇 → (Base‘𝑡) = (Base‘𝑇)) | 
| 47 | 46, 11 | eqtr4di 2247 | 
. . . . . . . . 9
⊢ (𝑡 = 𝑇 → (Base‘𝑡) = 𝑌) | 
| 48 | 47 | feq3d 5396 | 
. . . . . . . 8
⊢ (𝑡 = 𝑇 → (𝑓:𝑋⟶(Base‘𝑡) ↔ 𝑓:𝑋⟶𝑌)) | 
| 49 |   | fveq2 5558 | 
. . . . . . . . . . . 12
⊢ (𝑡 = 𝑇 → (+g‘𝑡) = (+g‘𝑇)) | 
| 50 |   | isghm.b | 
. . . . . . . . . . . 12
⊢  ⨣ =
(+g‘𝑇) | 
| 51 | 49, 50 | eqtr4di 2247 | 
. . . . . . . . . . 11
⊢ (𝑡 = 𝑇 → (+g‘𝑡) = ⨣ ) | 
| 52 | 51 | oveqd 5939 | 
. . . . . . . . . 10
⊢ (𝑡 = 𝑇 → ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣))) | 
| 53 | 52 | eqeq2d 2208 | 
. . . . . . . . 9
⊢ (𝑡 = 𝑇 → ((𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))) | 
| 54 | 53 | 2ralbidv 2521 | 
. . . . . . . 8
⊢ (𝑡 = 𝑇 → (∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)) ↔ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))) | 
| 55 | 48, 54 | anbi12d 473 | 
. . . . . . 7
⊢ (𝑡 = 𝑇 → ((𝑓:𝑋⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣))) ↔ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣))))) | 
| 56 | 55 | abbidv 2314 | 
. . . . . 6
⊢ (𝑡 = 𝑇 → {𝑓 ∣ (𝑓:𝑋⟶(Base‘𝑡) ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢)(+g‘𝑡)(𝑓‘𝑣)))} = {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))}) | 
| 57 | 45, 56, 1 | ovmpog 6057 | 
. . . . 5
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp ∧ {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ∈ V) → (𝑆 GrpHom 𝑇) = {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))}) | 
| 58 | 23, 57 | mpd3an3 1349 | 
. . . 4
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝑆 GrpHom 𝑇) = {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))}) | 
| 59 | 58 | eleq2d 2266 | 
. . 3
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝐹 ∈ (𝑆 GrpHom 𝑇) ↔ 𝐹 ∈ {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))})) | 
| 60 |   | simpr 110 | 
. . . . . . 7
⊢ (((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) ∧ 𝐹:𝑋⟶𝑌) → 𝐹:𝑋⟶𝑌) | 
| 61 | 10 | adantr 276 | 
. . . . . . 7
⊢ (((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) ∧ 𝐹:𝑋⟶𝑌) → 𝑋 ∈ V) | 
| 62 | 60, 61 | fexd 5792 | 
. . . . . 6
⊢ (((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) ∧ 𝐹:𝑋⟶𝑌) → 𝐹 ∈ V) | 
| 63 | 62 | ex 115 | 
. . . . 5
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝐹:𝑋⟶𝑌 → 𝐹 ∈ V)) | 
| 64 | 63 | adantrd 279 | 
. . . 4
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → ((𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))) → 𝐹 ∈ V)) | 
| 65 |   | feq1 5390 | 
. . . . . 6
⊢ (𝑓 = 𝐹 → (𝑓:𝑋⟶𝑌 ↔ 𝐹:𝑋⟶𝑌)) | 
| 66 |   | fveq1 5557 | 
. . . . . . . 8
⊢ (𝑓 = 𝐹 → (𝑓‘(𝑢 + 𝑣)) = (𝐹‘(𝑢 + 𝑣))) | 
| 67 |   | fveq1 5557 | 
. . . . . . . . 9
⊢ (𝑓 = 𝐹 → (𝑓‘𝑢) = (𝐹‘𝑢)) | 
| 68 |   | fveq1 5557 | 
. . . . . . . . 9
⊢ (𝑓 = 𝐹 → (𝑓‘𝑣) = (𝐹‘𝑣)) | 
| 69 | 67, 68 | oveq12d 5940 | 
. . . . . . . 8
⊢ (𝑓 = 𝐹 → ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))) | 
| 70 | 66, 69 | eqeq12d 2211 | 
. . . . . . 7
⊢ (𝑓 = 𝐹 → ((𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)) ↔ (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣)))) | 
| 71 | 70 | 2ralbidv 2521 | 
. . . . . 6
⊢ (𝑓 = 𝐹 → (∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)) ↔ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣)))) | 
| 72 | 65, 71 | anbi12d 473 | 
. . . . 5
⊢ (𝑓 = 𝐹 → ((𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣))) ↔ (𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))))) | 
| 73 | 72 | elab3g 2915 | 
. . . 4
⊢ (((𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))) → 𝐹 ∈ V) → (𝐹 ∈ {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ↔ (𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))))) | 
| 74 | 64, 73 | syl 14 | 
. . 3
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝐹 ∈ {𝑓 ∣ (𝑓:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝑓‘(𝑢 + 𝑣)) = ((𝑓‘𝑢) ⨣ (𝑓‘𝑣)))} ↔ (𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))))) | 
| 75 | 59, 74 | bitrd 188 | 
. 2
⊢ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) → (𝐹 ∈ (𝑆 GrpHom 𝑇) ↔ (𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))))) | 
| 76 | 2, 75 | biadanii 613 | 
1
⊢ (𝐹 ∈ (𝑆 GrpHom 𝑇) ↔ ((𝑆 ∈ Grp ∧ 𝑇 ∈ Grp) ∧ (𝐹:𝑋⟶𝑌 ∧ ∀𝑢 ∈ 𝑋 ∀𝑣 ∈ 𝑋 (𝐹‘(𝑢 + 𝑣)) = ((𝐹‘𝑢) ⨣ (𝐹‘𝑣))))) |