| Step | Hyp | Ref | Expression | 
						
							| 1 |  | setsms.x | ⊢ ( 𝜑  →  𝑋  =  ( Base ‘ 𝑀 ) ) | 
						
							| 2 |  | setsms.d | ⊢ ( 𝜑  →  𝐷  =  ( ( dist ‘ 𝑀 )  ↾  ( 𝑋  ×  𝑋 ) ) ) | 
						
							| 3 |  | setsms.k | ⊢ ( 𝜑  →  𝐾  =  ( 𝑀  sSet  〈 ( TopSet ‘ ndx ) ,  ( MetOpen ‘ 𝐷 ) 〉 ) ) | 
						
							| 4 |  | setsms.m | ⊢ ( 𝜑  →  𝑀  ∈  𝑉 ) | 
						
							| 5 | 1 2 3 4 | setsmstset | ⊢ ( 𝜑  →  ( MetOpen ‘ 𝐷 )  =  ( TopSet ‘ 𝐾 ) ) | 
						
							| 6 |  | df-mopn | ⊢ MetOpen  =  ( 𝑥  ∈  ∪  ran  ∞Met  ↦  ( topGen ‘ ran  ( ball ‘ 𝑥 ) ) ) | 
						
							| 7 | 6 | dmmptss | ⊢ dom  MetOpen  ⊆  ∪  ran  ∞Met | 
						
							| 8 | 7 | sseli | ⊢ ( 𝐷  ∈  dom  MetOpen  →  𝐷  ∈  ∪  ran  ∞Met ) | 
						
							| 9 |  | simpr | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  𝐷  ∈  ∪  ran  ∞Met ) | 
						
							| 10 |  | xmetunirn | ⊢ ( 𝐷  ∈  ∪  ran  ∞Met  ↔  𝐷  ∈  ( ∞Met ‘ dom  dom  𝐷 ) ) | 
						
							| 11 | 9 10 | sylib | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  𝐷  ∈  ( ∞Met ‘ dom  dom  𝐷 ) ) | 
						
							| 12 |  | eqid | ⊢ ( MetOpen ‘ 𝐷 )  =  ( MetOpen ‘ 𝐷 ) | 
						
							| 13 | 12 | mopnuni | ⊢ ( 𝐷  ∈  ( ∞Met ‘ dom  dom  𝐷 )  →  dom  dom  𝐷  =  ∪  ( MetOpen ‘ 𝐷 ) ) | 
						
							| 14 | 11 13 | syl | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  dom  dom  𝐷  =  ∪  ( MetOpen ‘ 𝐷 ) ) | 
						
							| 15 | 2 | dmeqd | ⊢ ( 𝜑  →  dom  𝐷  =  dom  ( ( dist ‘ 𝑀 )  ↾  ( 𝑋  ×  𝑋 ) ) ) | 
						
							| 16 |  | dmres | ⊢ dom  ( ( dist ‘ 𝑀 )  ↾  ( 𝑋  ×  𝑋 ) )  =  ( ( 𝑋  ×  𝑋 )  ∩  dom  ( dist ‘ 𝑀 ) ) | 
						
							| 17 | 15 16 | eqtrdi | ⊢ ( 𝜑  →  dom  𝐷  =  ( ( 𝑋  ×  𝑋 )  ∩  dom  ( dist ‘ 𝑀 ) ) ) | 
						
							| 18 |  | inss1 | ⊢ ( ( 𝑋  ×  𝑋 )  ∩  dom  ( dist ‘ 𝑀 ) )  ⊆  ( 𝑋  ×  𝑋 ) | 
						
							| 19 | 17 18 | eqsstrdi | ⊢ ( 𝜑  →  dom  𝐷  ⊆  ( 𝑋  ×  𝑋 ) ) | 
						
							| 20 |  | dmss | ⊢ ( dom  𝐷  ⊆  ( 𝑋  ×  𝑋 )  →  dom  dom  𝐷  ⊆  dom  ( 𝑋  ×  𝑋 ) ) | 
						
							| 21 | 19 20 | syl | ⊢ ( 𝜑  →  dom  dom  𝐷  ⊆  dom  ( 𝑋  ×  𝑋 ) ) | 
						
							| 22 |  | dmxpid | ⊢ dom  ( 𝑋  ×  𝑋 )  =  𝑋 | 
						
							| 23 | 21 22 | sseqtrdi | ⊢ ( 𝜑  →  dom  dom  𝐷  ⊆  𝑋 ) | 
						
							| 24 | 23 | adantr | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  dom  dom  𝐷  ⊆  𝑋 ) | 
						
							| 25 | 14 24 | eqsstrrd | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  ∪  ( MetOpen ‘ 𝐷 )  ⊆  𝑋 ) | 
						
							| 26 |  | sspwuni | ⊢ ( ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋  ↔  ∪  ( MetOpen ‘ 𝐷 )  ⊆  𝑋 ) | 
						
							| 27 | 25 26 | sylibr | ⊢ ( ( 𝜑  ∧  𝐷  ∈  ∪  ran  ∞Met )  →  ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋 ) | 
						
							| 28 | 27 | ex | ⊢ ( 𝜑  →  ( 𝐷  ∈  ∪  ran  ∞Met  →  ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋 ) ) | 
						
							| 29 | 8 28 | syl5 | ⊢ ( 𝜑  →  ( 𝐷  ∈  dom  MetOpen  →  ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋 ) ) | 
						
							| 30 |  | ndmfv | ⊢ ( ¬  𝐷  ∈  dom  MetOpen  →  ( MetOpen ‘ 𝐷 )  =  ∅ ) | 
						
							| 31 |  | 0ss | ⊢ ∅  ⊆  𝒫  𝑋 | 
						
							| 32 | 30 31 | eqsstrdi | ⊢ ( ¬  𝐷  ∈  dom  MetOpen  →  ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋 ) | 
						
							| 33 | 29 32 | pm2.61d1 | ⊢ ( 𝜑  →  ( MetOpen ‘ 𝐷 )  ⊆  𝒫  𝑋 ) | 
						
							| 34 | 1 2 3 | setsmsbas | ⊢ ( 𝜑  →  𝑋  =  ( Base ‘ 𝐾 ) ) | 
						
							| 35 | 34 | pweqd | ⊢ ( 𝜑  →  𝒫  𝑋  =  𝒫  ( Base ‘ 𝐾 ) ) | 
						
							| 36 | 33 5 35 | 3sstr3d | ⊢ ( 𝜑  →  ( TopSet ‘ 𝐾 )  ⊆  𝒫  ( Base ‘ 𝐾 ) ) | 
						
							| 37 |  | eqid | ⊢ ( Base ‘ 𝐾 )  =  ( Base ‘ 𝐾 ) | 
						
							| 38 |  | eqid | ⊢ ( TopSet ‘ 𝐾 )  =  ( TopSet ‘ 𝐾 ) | 
						
							| 39 | 37 38 | topnid | ⊢ ( ( TopSet ‘ 𝐾 )  ⊆  𝒫  ( Base ‘ 𝐾 )  →  ( TopSet ‘ 𝐾 )  =  ( TopOpen ‘ 𝐾 ) ) | 
						
							| 40 | 36 39 | syl | ⊢ ( 𝜑  →  ( TopSet ‘ 𝐾 )  =  ( TopOpen ‘ 𝐾 ) ) | 
						
							| 41 | 5 40 | eqtrd | ⊢ ( 𝜑  →  ( MetOpen ‘ 𝐷 )  =  ( TopOpen ‘ 𝐾 ) ) |