| Step | Hyp | Ref | Expression | 
						
							| 1 |  | xrltletr | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) ) | 
						
							| 2 |  | id | ⊢ ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 )  →  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) ) | 
						
							| 3 | 2 | impcom | ⊢ ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  𝐴  <  𝐶 ) | 
						
							| 4 |  | xrltnle | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( 𝐴  <  𝐶  ↔  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 5 | 4 | 3adant2 | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( 𝐴  <  𝐶  ↔  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 6 | 5 | biimpd | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( 𝐴  <  𝐶  →  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 7 | 6 | imp | ⊢ ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  𝐴  <  𝐶 )  →  ¬  𝐶  ≤  𝐴 ) | 
						
							| 8 | 7 | olcd | ⊢ ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  𝐴  <  𝐶 )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 9 | 8 | expcom | ⊢ ( 𝐴  <  𝐶  →  ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) | 
						
							| 10 | 3 9 | syl | ⊢ ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) | 
						
							| 11 | 10 | ex | ⊢ ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 )  →  ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) ) | 
						
							| 12 | 11 | com23 | ⊢ ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) ) | 
						
							| 13 | 12 | impd | ⊢ ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) | 
						
							| 14 |  | id | ⊢ ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 ) ) | 
						
							| 15 | 14 | orcd | ⊢ ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 16 | 15 | a1d | ⊢ ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) ) | 
						
							| 17 | 13 16 | pm2.61i | ⊢ ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 18 |  | df-3an | ⊢ ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 )  ↔  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∧  𝐶  ≤  𝐴 ) ) | 
						
							| 19 | 18 | notbii | ⊢ ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 )  ↔  ¬  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∧  𝐶  ≤  𝐴 ) ) | 
						
							| 20 |  | ianor | ⊢ ( ¬  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∧  𝐶  ≤  𝐴 )  ↔  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 21 | 19 20 | bitri | ⊢ ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 )  ↔  ( ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  ∨  ¬  𝐶  ≤  𝐴 ) ) | 
						
							| 22 | 17 21 | sylibr | ⊢ ( ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  ∧  ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 ) )  →  ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 ) ) | 
						
							| 23 | 22 | ex | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ( ( ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶 )  →  𝐴  <  𝐶 )  →  ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 ) ) ) | 
						
							| 24 | 1 23 | mpd | ⊢ ( ( 𝐴  ∈  ℝ*  ∧  𝐵  ∈  ℝ*  ∧  𝐶  ∈  ℝ* )  →  ¬  ( 𝐴  <  𝐵  ∧  𝐵  ≤  𝐶  ∧  𝐶  ≤  𝐴 ) ) |