| Step | Hyp | Ref | Expression | 
						
							| 1 |  | negsproplem.1 | ⊢ ( 𝜑  →  ∀ 𝑥  ∈   No  ∀ 𝑦  ∈   No  ( ( (  bday  ‘ 𝑥 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑥 )  ∈   No   ∧  ( 𝑥  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 ) ) ) ) ) | 
						
							| 2 |  | negsproplem1.1 | ⊢ ( 𝜑  →  𝑋  ∈   No  ) | 
						
							| 3 |  | negsproplem1.2 | ⊢ ( 𝜑  →  𝑌  ∈   No  ) | 
						
							| 4 |  | negsproplem1.3 | ⊢ ( 𝜑  →  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑌 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) ) ) | 
						
							| 5 | 2 3 | jca | ⊢ ( 𝜑  →  ( 𝑋  ∈   No   ∧  𝑌  ∈   No  ) ) | 
						
							| 6 |  | fveq2 | ⊢ ( 𝑥  =  𝑋  →  (  bday  ‘ 𝑥 )  =  (  bday  ‘ 𝑋 ) ) | 
						
							| 7 | 6 | uneq1d | ⊢ ( 𝑥  =  𝑋  →  ( (  bday  ‘ 𝑥 )  ∪  (  bday  ‘ 𝑦 ) )  =  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) ) ) | 
						
							| 8 | 7 | eleq1d | ⊢ ( 𝑥  =  𝑋  →  ( ( (  bday  ‘ 𝑥 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  ↔  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) ) ) ) | 
						
							| 9 |  | fveq2 | ⊢ ( 𝑥  =  𝑋  →  (  -us  ‘ 𝑥 )  =  (  -us  ‘ 𝑋 ) ) | 
						
							| 10 | 9 | eleq1d | ⊢ ( 𝑥  =  𝑋  →  ( (  -us  ‘ 𝑥 )  ∈   No   ↔  (  -us  ‘ 𝑋 )  ∈   No  ) ) | 
						
							| 11 |  | breq1 | ⊢ ( 𝑥  =  𝑋  →  ( 𝑥  <s  𝑦  ↔  𝑋  <s  𝑦 ) ) | 
						
							| 12 | 9 | breq2d | ⊢ ( 𝑥  =  𝑋  →  ( (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 )  ↔  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) ) | 
						
							| 13 | 11 12 | imbi12d | ⊢ ( 𝑥  =  𝑋  →  ( ( 𝑥  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 ) )  ↔  ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) ) ) | 
						
							| 14 | 10 13 | anbi12d | ⊢ ( 𝑥  =  𝑋  →  ( ( (  -us  ‘ 𝑥 )  ∈   No   ∧  ( 𝑥  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 ) ) )  ↔  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) ) ) ) | 
						
							| 15 | 8 14 | imbi12d | ⊢ ( 𝑥  =  𝑋  →  ( ( ( (  bday  ‘ 𝑥 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑥 )  ∈   No   ∧  ( 𝑥  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 ) ) ) )  ↔  ( ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) ) ) ) ) | 
						
							| 16 |  | fveq2 | ⊢ ( 𝑦  =  𝑌  →  (  bday  ‘ 𝑦 )  =  (  bday  ‘ 𝑌 ) ) | 
						
							| 17 | 16 | uneq2d | ⊢ ( 𝑦  =  𝑌  →  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) )  =  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑌 ) ) ) | 
						
							| 18 | 17 | eleq1d | ⊢ ( 𝑦  =  𝑌  →  ( ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  ↔  ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑌 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) ) ) ) | 
						
							| 19 |  | breq2 | ⊢ ( 𝑦  =  𝑌  →  ( 𝑋  <s  𝑦  ↔  𝑋  <s  𝑌 ) ) | 
						
							| 20 |  | fveq2 | ⊢ ( 𝑦  =  𝑌  →  (  -us  ‘ 𝑦 )  =  (  -us  ‘ 𝑌 ) ) | 
						
							| 21 | 20 | breq1d | ⊢ ( 𝑦  =  𝑌  →  ( (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 )  ↔  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) | 
						
							| 22 | 19 21 | imbi12d | ⊢ ( 𝑦  =  𝑌  →  ( ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) )  ↔  ( 𝑋  <s  𝑌  →  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) ) | 
						
							| 23 | 22 | anbi2d | ⊢ ( 𝑦  =  𝑌  →  ( ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) )  ↔  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑌  →  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) ) ) | 
						
							| 24 | 18 23 | imbi12d | ⊢ ( 𝑦  =  𝑌  →  ( ( ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑋 ) ) ) )  ↔  ( ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑌 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑌  →  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) ) ) ) | 
						
							| 25 | 15 24 | rspc2v | ⊢ ( ( 𝑋  ∈   No   ∧  𝑌  ∈   No  )  →  ( ∀ 𝑥  ∈   No  ∀ 𝑦  ∈   No  ( ( (  bday  ‘ 𝑥 )  ∪  (  bday  ‘ 𝑦 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑥 )  ∈   No   ∧  ( 𝑥  <s  𝑦  →  (  -us  ‘ 𝑦 )  <s  (  -us  ‘ 𝑥 ) ) ) )  →  ( ( (  bday  ‘ 𝑋 )  ∪  (  bday  ‘ 𝑌 ) )  ∈  ( (  bday  ‘ 𝐴 )  ∪  (  bday  ‘ 𝐵 ) )  →  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑌  →  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) ) ) ) | 
						
							| 26 | 5 1 4 25 | syl3c | ⊢ ( 𝜑  →  ( (  -us  ‘ 𝑋 )  ∈   No   ∧  ( 𝑋  <s  𝑌  →  (  -us  ‘ 𝑌 )  <s  (  -us  ‘ 𝑋 ) ) ) ) |