| Step | Hyp | Ref | Expression | 
						
							| 1 |  | peano2re | ⊢ ( 𝑥  ∈  ℝ  →  ( 𝑥  +  1 )  ∈  ℝ ) | 
						
							| 2 | 1 | adantr | ⊢ ( ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( 𝑥  +  1 )  ∈  ℝ ) | 
						
							| 3 | 2 | a1i | ⊢ ( 𝐴  ⊆  ℝ  →  ( ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( 𝑥  +  1 )  ∈  ℝ ) ) | 
						
							| 4 |  | ssel | ⊢ ( 𝐴  ⊆  ℝ  →  ( 𝑦  ∈  𝐴  →  𝑦  ∈  ℝ ) ) | 
						
							| 5 |  | sn-ltp1 | ⊢ ( 𝑥  ∈  ℝ  →  𝑥  <  ( 𝑥  +  1 ) ) | 
						
							| 6 | 1 | ancli | ⊢ ( 𝑥  ∈  ℝ  →  ( 𝑥  ∈  ℝ  ∧  ( 𝑥  +  1 )  ∈  ℝ ) ) | 
						
							| 7 |  | lttr | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ  ∧  ( 𝑥  +  1 )  ∈  ℝ )  →  ( ( 𝑦  <  𝑥  ∧  𝑥  <  ( 𝑥  +  1 ) )  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 8 | 7 | 3expb | ⊢ ( ( 𝑦  ∈  ℝ  ∧  ( 𝑥  ∈  ℝ  ∧  ( 𝑥  +  1 )  ∈  ℝ ) )  →  ( ( 𝑦  <  𝑥  ∧  𝑥  <  ( 𝑥  +  1 ) )  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 9 | 6 8 | sylan2 | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ )  →  ( ( 𝑦  <  𝑥  ∧  𝑥  <  ( 𝑥  +  1 ) )  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 10 | 5 9 | sylan2i | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ )  →  ( ( 𝑦  <  𝑥  ∧  𝑥  ∈  ℝ )  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 11 | 10 | exp4b | ⊢ ( 𝑦  ∈  ℝ  →  ( 𝑥  ∈  ℝ  →  ( 𝑦  <  𝑥  →  ( 𝑥  ∈  ℝ  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) ) | 
						
							| 12 | 11 | com34 | ⊢ ( 𝑦  ∈  ℝ  →  ( 𝑥  ∈  ℝ  →  ( 𝑥  ∈  ℝ  →  ( 𝑦  <  𝑥  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) ) | 
						
							| 13 | 12 | pm2.43d | ⊢ ( 𝑦  ∈  ℝ  →  ( 𝑥  ∈  ℝ  →  ( 𝑦  <  𝑥  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 14 | 13 | imp | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ )  →  ( 𝑦  <  𝑥  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 15 |  | breq1 | ⊢ ( 𝑦  =  𝑥  →  ( 𝑦  <  ( 𝑥  +  1 )  ↔  𝑥  <  ( 𝑥  +  1 ) ) ) | 
						
							| 16 | 5 15 | syl5ibrcom | ⊢ ( 𝑥  ∈  ℝ  →  ( 𝑦  =  𝑥  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 17 | 16 | adantl | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ )  →  ( 𝑦  =  𝑥  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 18 | 14 17 | jaod | ⊢ ( ( 𝑦  ∈  ℝ  ∧  𝑥  ∈  ℝ )  →  ( ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 19 | 18 | ex | ⊢ ( 𝑦  ∈  ℝ  →  ( 𝑥  ∈  ℝ  →  ( ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 20 | 4 19 | syl6 | ⊢ ( 𝐴  ⊆  ℝ  →  ( 𝑦  ∈  𝐴  →  ( 𝑥  ∈  ℝ  →  ( ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) ) | 
						
							| 21 | 20 | com23 | ⊢ ( 𝐴  ⊆  ℝ  →  ( 𝑥  ∈  ℝ  →  ( 𝑦  ∈  𝐴  →  ( ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) ) | 
						
							| 22 | 21 | imp | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝑥  ∈  ℝ )  →  ( 𝑦  ∈  𝐴  →  ( ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 23 | 22 | a2d | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝑥  ∈  ℝ )  →  ( ( 𝑦  ∈  𝐴  →  ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( 𝑦  ∈  𝐴  →  𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 24 | 23 | ralimdv2 | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝑥  ∈  ℝ )  →  ( ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 25 | 24 | expimpd | ⊢ ( 𝐴  ⊆  ℝ  →  ( ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 26 | 3 25 | jcad | ⊢ ( 𝐴  ⊆  ℝ  →  ( ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( ( 𝑥  +  1 )  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 27 |  | ovex | ⊢ ( 𝑥  +  1 )  ∈  V | 
						
							| 28 |  | eleq1 | ⊢ ( 𝑧  =  ( 𝑥  +  1 )  →  ( 𝑧  ∈  ℝ  ↔  ( 𝑥  +  1 )  ∈  ℝ ) ) | 
						
							| 29 |  | breq2 | ⊢ ( 𝑧  =  ( 𝑥  +  1 )  →  ( 𝑦  <  𝑧  ↔  𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 30 | 29 | ralbidv | ⊢ ( 𝑧  =  ( 𝑥  +  1 )  →  ( ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧  ↔  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) ) ) | 
						
							| 31 | 28 30 | anbi12d | ⊢ ( 𝑧  =  ( 𝑥  +  1 )  →  ( ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 )  ↔  ( ( 𝑥  +  1 )  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) ) ) ) | 
						
							| 32 | 27 31 | spcev | ⊢ ( ( ( 𝑥  +  1 )  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  ( 𝑥  +  1 ) )  →  ∃ 𝑧 ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 ) ) | 
						
							| 33 | 26 32 | syl6 | ⊢ ( 𝐴  ⊆  ℝ  →  ( ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ∃ 𝑧 ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 ) ) ) | 
						
							| 34 | 33 | exlimdv | ⊢ ( 𝐴  ⊆  ℝ  →  ( ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ∃ 𝑧 ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 ) ) ) | 
						
							| 35 |  | eleq1 | ⊢ ( 𝑧  =  𝑥  →  ( 𝑧  ∈  ℝ  ↔  𝑥  ∈  ℝ ) ) | 
						
							| 36 |  | breq2 | ⊢ ( 𝑧  =  𝑥  →  ( 𝑦  <  𝑧  ↔  𝑦  <  𝑥 ) ) | 
						
							| 37 | 36 | ralbidv | ⊢ ( 𝑧  =  𝑥  →  ( ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧  ↔  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 38 | 35 37 | anbi12d | ⊢ ( 𝑧  =  𝑥  →  ( ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 )  ↔  ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) ) | 
						
							| 39 | 38 | cbvexvw | ⊢ ( ∃ 𝑧 ( 𝑧  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑧 )  ↔  ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 40 | 34 39 | imbitrdi | ⊢ ( 𝐴  ⊆  ℝ  →  ( ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) ) | 
						
							| 41 |  | df-rex | ⊢ ( ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  ↔  ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) ) ) | 
						
							| 42 |  | df-rex | ⊢ ( ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥  ↔  ∃ 𝑥 ( 𝑥  ∈  ℝ  ∧  ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 43 | 40 41 42 | 3imtr4g | ⊢ ( 𝐴  ⊆  ℝ  →  ( ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 44 | 43 | adantr | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅ )  →  ( ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 )  →  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 45 | 44 | imdistani | ⊢ ( ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅ )  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅ )  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 46 |  | df-3an | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  ↔  ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅ )  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) ) ) | 
						
							| 47 |  | df-3an | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 )  ↔  ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅ )  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 48 | 45 46 47 | 3imtr4i | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 ) ) | 
						
							| 49 |  | axsup | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 𝑦  <  𝑥 )  →  ∃ 𝑥  ∈  ℝ ( ∀ 𝑦  ∈  𝐴 ¬  𝑥  <  𝑦  ∧  ∀ 𝑦  ∈  ℝ ( 𝑦  <  𝑥  →  ∃ 𝑧  ∈  𝐴 𝑦  <  𝑧 ) ) ) | 
						
							| 50 | 48 49 | syl | ⊢ ( ( 𝐴  ⊆  ℝ  ∧  𝐴  ≠  ∅  ∧  ∃ 𝑥  ∈  ℝ ∀ 𝑦  ∈  𝐴 ( 𝑦  <  𝑥  ∨  𝑦  =  𝑥 ) )  →  ∃ 𝑥  ∈  ℝ ( ∀ 𝑦  ∈  𝐴 ¬  𝑥  <  𝑦  ∧  ∀ 𝑦  ∈  ℝ ( 𝑦  <  𝑥  →  ∃ 𝑧  ∈  𝐴 𝑦  <  𝑧 ) ) ) |