| Step | Hyp | Ref | Expression | 
						
							| 1 |  | df-ico | ⊢ [,)  =  ( 𝑥  ∈  ℝ* ,  𝑦  ∈  ℝ*  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 2 | 1 | reseq1i | ⊢ ( [,)  ↾  ( ℝ  ×  ℝ ) )  =  ( ( 𝑥  ∈  ℝ* ,  𝑦  ∈  ℝ*  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } )  ↾  ( ℝ  ×  ℝ ) ) | 
						
							| 3 |  | ressxr | ⊢ ℝ  ⊆  ℝ* | 
						
							| 4 |  | resmpo | ⊢ ( ( ℝ  ⊆  ℝ*  ∧  ℝ  ⊆  ℝ* )  →  ( ( 𝑥  ∈  ℝ* ,  𝑦  ∈  ℝ*  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } )  ↾  ( ℝ  ×  ℝ ) )  =  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) ) | 
						
							| 5 | 3 3 4 | mp2an | ⊢ ( ( 𝑥  ∈  ℝ* ,  𝑦  ∈  ℝ*  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } )  ↾  ( ℝ  ×  ℝ ) )  =  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 6 | 2 5 | eqtri | ⊢ ( [,)  ↾  ( ℝ  ×  ℝ ) )  =  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 7 | 6 | rneqi | ⊢ ran  ( [,)  ↾  ( ℝ  ×  ℝ ) )  =  ran  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 8 | 7 | eleq2i | ⊢ ( 𝐴  ∈  ran  ( [,)  ↾  ( ℝ  ×  ℝ ) )  ↔  𝐴  ∈  ran  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) ) | 
						
							| 9 |  | eqid | ⊢ ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } )  =  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 10 |  | xrex | ⊢ ℝ*  ∈  V | 
						
							| 11 | 10 | rabex | ⊢ { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) }  ∈  V | 
						
							| 12 | 9 11 | elrnmpo | ⊢ ( 𝐴  ∈  ran  ( 𝑥  ∈  ℝ ,  𝑦  ∈  ℝ  ↦  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } )  ↔  ∃ 𝑥  ∈  ℝ ∃ 𝑦  ∈  ℝ 𝐴  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 13 | 3 | sseli | ⊢ ( 𝑥  ∈  ℝ  →  𝑥  ∈  ℝ* ) | 
						
							| 14 | 13 | adantr | ⊢ ( ( 𝑥  ∈  ℝ  ∧  𝑦  ∈  ℝ )  →  𝑥  ∈  ℝ* ) | 
						
							| 15 | 3 | sseli | ⊢ ( 𝑦  ∈  ℝ  →  𝑦  ∈  ℝ* ) | 
						
							| 16 | 15 | adantl | ⊢ ( ( 𝑥  ∈  ℝ  ∧  𝑦  ∈  ℝ )  →  𝑦  ∈  ℝ* ) | 
						
							| 17 |  | icoval | ⊢ ( ( 𝑥  ∈  ℝ*  ∧  𝑦  ∈  ℝ* )  →  ( 𝑥 [,) 𝑦 )  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 18 | 14 16 17 | syl2anc | ⊢ ( ( 𝑥  ∈  ℝ  ∧  𝑦  ∈  ℝ )  →  ( 𝑥 [,) 𝑦 )  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) } ) | 
						
							| 19 | 18 | eqcomd | ⊢ ( ( 𝑥  ∈  ℝ  ∧  𝑦  ∈  ℝ )  →  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) }  =  ( 𝑥 [,) 𝑦 ) ) | 
						
							| 20 | 19 | eqeq2d | ⊢ ( ( 𝑥  ∈  ℝ  ∧  𝑦  ∈  ℝ )  →  ( 𝐴  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) }  ↔  𝐴  =  ( 𝑥 [,) 𝑦 ) ) ) | 
						
							| 21 | 20 | rexbidva | ⊢ ( 𝑥  ∈  ℝ  →  ( ∃ 𝑦  ∈  ℝ 𝐴  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) }  ↔  ∃ 𝑦  ∈  ℝ 𝐴  =  ( 𝑥 [,) 𝑦 ) ) ) | 
						
							| 22 | 21 | rexbiia | ⊢ ( ∃ 𝑥  ∈  ℝ ∃ 𝑦  ∈  ℝ 𝐴  =  { 𝑧  ∈  ℝ*  ∣  ( 𝑥  ≤  𝑧  ∧  𝑧  <  𝑦 ) }  ↔  ∃ 𝑥  ∈  ℝ ∃ 𝑦  ∈  ℝ 𝐴  =  ( 𝑥 [,) 𝑦 ) ) | 
						
							| 23 | 8 12 22 | 3bitri | ⊢ ( 𝐴  ∈  ran  ( [,)  ↾  ( ℝ  ×  ℝ ) )  ↔  ∃ 𝑥  ∈  ℝ ∃ 𝑦  ∈  ℝ 𝐴  =  ( 𝑥 [,) 𝑦 ) ) |