| Step | Hyp | Ref | Expression | 
						
							| 1 |  | psraddclOLD.s | ⊢ 𝑆  =  ( 𝐼  mPwSer  𝑅 ) | 
						
							| 2 |  | psraddclOLD.b | ⊢ 𝐵  =  ( Base ‘ 𝑆 ) | 
						
							| 3 |  | psraddclOLD.p | ⊢  +   =  ( +g ‘ 𝑆 ) | 
						
							| 4 |  | psraddclOLD.r | ⊢ ( 𝜑  →  𝑅  ∈  Grp ) | 
						
							| 5 |  | psraddclOLD.x | ⊢ ( 𝜑  →  𝑋  ∈  𝐵 ) | 
						
							| 6 |  | psraddclOLD.y | ⊢ ( 𝜑  →  𝑌  ∈  𝐵 ) | 
						
							| 7 |  | eqid | ⊢ ( Base ‘ 𝑅 )  =  ( Base ‘ 𝑅 ) | 
						
							| 8 |  | eqid | ⊢ ( +g ‘ 𝑅 )  =  ( +g ‘ 𝑅 ) | 
						
							| 9 | 7 8 | grpcl | ⊢ ( ( 𝑅  ∈  Grp  ∧  𝑥  ∈  ( Base ‘ 𝑅 )  ∧  𝑦  ∈  ( Base ‘ 𝑅 ) )  →  ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  ∈  ( Base ‘ 𝑅 ) ) | 
						
							| 10 | 9 | 3expb | ⊢ ( ( 𝑅  ∈  Grp  ∧  ( 𝑥  ∈  ( Base ‘ 𝑅 )  ∧  𝑦  ∈  ( Base ‘ 𝑅 ) ) )  →  ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  ∈  ( Base ‘ 𝑅 ) ) | 
						
							| 11 | 4 10 | sylan | ⊢ ( ( 𝜑  ∧  ( 𝑥  ∈  ( Base ‘ 𝑅 )  ∧  𝑦  ∈  ( Base ‘ 𝑅 ) ) )  →  ( 𝑥 ( +g ‘ 𝑅 ) 𝑦 )  ∈  ( Base ‘ 𝑅 ) ) | 
						
							| 12 |  | eqid | ⊢ { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin }  =  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } | 
						
							| 13 | 1 7 12 2 5 | psrelbas | ⊢ ( 𝜑  →  𝑋 : { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ⟶ ( Base ‘ 𝑅 ) ) | 
						
							| 14 | 1 7 12 2 6 | psrelbas | ⊢ ( 𝜑  →  𝑌 : { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ⟶ ( Base ‘ 𝑅 ) ) | 
						
							| 15 |  | ovex | ⊢ ( ℕ0  ↑m  𝐼 )  ∈  V | 
						
							| 16 | 15 | rabex | ⊢ { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin }  ∈  V | 
						
							| 17 | 16 | a1i | ⊢ ( 𝜑  →  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin }  ∈  V ) | 
						
							| 18 |  | inidm | ⊢ ( { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin }  ∩  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } )  =  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } | 
						
							| 19 | 11 13 14 17 17 18 | off | ⊢ ( 𝜑  →  ( 𝑋  ∘f  ( +g ‘ 𝑅 ) 𝑌 ) : { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ⟶ ( Base ‘ 𝑅 ) ) | 
						
							| 20 |  | fvex | ⊢ ( Base ‘ 𝑅 )  ∈  V | 
						
							| 21 | 20 16 | elmap | ⊢ ( ( 𝑋  ∘f  ( +g ‘ 𝑅 ) 𝑌 )  ∈  ( ( Base ‘ 𝑅 )  ↑m  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } )  ↔  ( 𝑋  ∘f  ( +g ‘ 𝑅 ) 𝑌 ) : { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ⟶ ( Base ‘ 𝑅 ) ) | 
						
							| 22 | 19 21 | sylibr | ⊢ ( 𝜑  →  ( 𝑋  ∘f  ( +g ‘ 𝑅 ) 𝑌 )  ∈  ( ( Base ‘ 𝑅 )  ↑m  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ) ) | 
						
							| 23 | 1 2 8 3 5 6 | psradd | ⊢ ( 𝜑  →  ( 𝑋  +  𝑌 )  =  ( 𝑋  ∘f  ( +g ‘ 𝑅 ) 𝑌 ) ) | 
						
							| 24 |  | reldmpsr | ⊢ Rel  dom   mPwSer | 
						
							| 25 | 24 1 2 | elbasov | ⊢ ( 𝑋  ∈  𝐵  →  ( 𝐼  ∈  V  ∧  𝑅  ∈  V ) ) | 
						
							| 26 | 5 25 | syl | ⊢ ( 𝜑  →  ( 𝐼  ∈  V  ∧  𝑅  ∈  V ) ) | 
						
							| 27 | 26 | simpld | ⊢ ( 𝜑  →  𝐼  ∈  V ) | 
						
							| 28 | 1 7 12 2 27 | psrbas | ⊢ ( 𝜑  →  𝐵  =  ( ( Base ‘ 𝑅 )  ↑m  { 𝑓  ∈  ( ℕ0  ↑m  𝐼 )  ∣  ( ◡ 𝑓  “  ℕ )  ∈  Fin } ) ) | 
						
							| 29 | 22 23 28 | 3eltr4d | ⊢ ( 𝜑  →  ( 𝑋  +  𝑌 )  ∈  𝐵 ) |