Theorem precsexlem4

Description: Lemma for surreal reciprocals. Calculate the value of the recursive left function at a successor. (Contributed by Scott Fenton, 13-Mar-2025)

	Ref	Expression
Hypotheses	precsexlem.1	⊢ 𝐹 = rec ( ( 𝑝 ∈ V ↦ ⦋ ( 1st ‘ 𝑝 ) / 𝑙 ⦌ ⦋ ( 2nd ‘ 𝑝 ) / 𝑟 ⦌ ⟨ ( 𝑙 ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( 𝑟 ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) , ⟨ { 0s } , ∅ ⟩ )
	precsexlem.2	⊢ 𝐿 = ( 1st ∘ 𝐹 )
	precsexlem.3	⊢ 𝑅 = ( 2nd ∘ 𝐹 )
Assertion	precsexlem4	⊢ ( 𝐼 ∈ ω → ( 𝐿 ‘ suc 𝐼 ) = ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) )

Proof

Step	Hyp	Ref	Expression
1		precsexlem.1	⊢ 𝐹 = rec ( ( 𝑝 ∈ V ↦ ⦋ ( 1st ‘ 𝑝 ) / 𝑙 ⦌ ⦋ ( 2nd ‘ 𝑝 ) / 𝑟 ⦌ ⟨ ( 𝑙 ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( 𝑟 ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) , ⟨ { 0s } , ∅ ⟩ )
2		precsexlem.2	⊢ 𝐿 = ( 1st ∘ 𝐹 )
3		precsexlem.3	⊢ 𝑅 = ( 2nd ∘ 𝐹 )
4	2	fveq1i	⊢ ( 𝐿 ‘ suc 𝐼 ) = ( ( 1st ∘ 𝐹 ) ‘ suc 𝐼 )
5		peano2	⊢ ( 𝐼 ∈ ω → suc 𝐼 ∈ ω )
6		nnon	⊢ ( suc 𝐼 ∈ ω → suc 𝐼 ∈ On )
7		rdgfnon	⊢ rec ( ( 𝑝 ∈ V ↦ ⦋ ( 1st ‘ 𝑝 ) / 𝑙 ⦌ ⦋ ( 2nd ‘ 𝑝 ) / 𝑟 ⦌ ⟨ ( 𝑙 ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( 𝑟 ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) , ⟨ { 0s } , ∅ ⟩ ) Fn On
8	1	fneq1i	⊢ ( 𝐹 Fn On ↔ rec ( ( 𝑝 ∈ V ↦ ⦋ ( 1st ‘ 𝑝 ) / 𝑙 ⦌ ⦋ ( 2nd ‘ 𝑝 ) / 𝑟 ⦌ ⟨ ( 𝑙 ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( 𝑟 ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ 𝑙 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ 𝑟 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) , ⟨ { 0s } , ∅ ⟩ ) Fn On )
9	7 8	mpbir	⊢ 𝐹 Fn On
10		fvco2	⊢ ( ( 𝐹 Fn On ∧ suc 𝐼 ∈ On ) → ( ( 1st ∘ 𝐹 ) ‘ suc 𝐼 ) = ( 1st ‘ ( 𝐹 ‘ suc 𝐼 ) ) )
11	9 10	mpan	⊢ ( suc 𝐼 ∈ On → ( ( 1st ∘ 𝐹 ) ‘ suc 𝐼 ) = ( 1st ‘ ( 𝐹 ‘ suc 𝐼 ) ) )
12	5 6 11	3syl	⊢ ( 𝐼 ∈ ω → ( ( 1st ∘ 𝐹 ) ‘ suc 𝐼 ) = ( 1st ‘ ( 𝐹 ‘ suc 𝐼 ) ) )
13	1 2 3	precsexlem3	⊢ ( 𝐼 ∈ ω → ( 𝐹 ‘ suc 𝐼 ) = ⟨ ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( ( 𝑅 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ )
14	13	fveq2d	⊢ ( 𝐼 ∈ ω → ( 1st ‘ ( 𝐹 ‘ suc 𝐼 ) ) = ( 1st ‘ ⟨ ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( ( 𝑅 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) )
15		fvex	⊢ ( 𝐿 ‘ 𝐼 ) ∈ V
16		fvex	⊢ ( R ‘ 𝐴 ) ∈ V
17	16 15	ab2rexex	⊢ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∈ V
18		fvex	⊢ ( L ‘ 𝐴 ) ∈ V
19	18	rabex	⊢ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∈ V
20		fvex	⊢ ( 𝑅 ‘ 𝐼 ) ∈ V
21	19 20	ab2rexex	⊢ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ∈ V
22	17 21	unex	⊢ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ∈ V
23	15 22	unex	⊢ ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) ∈ V
24	19 15	ab2rexex	⊢ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∈ V
25	16 20	ab2rexex	⊢ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ∈ V
26	24 25	unex	⊢ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ∈ V
27	20 26	unex	⊢ ( ( 𝑅 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ∈ V
28	23 27	op1st	⊢ ( 1st ‘ ⟨ ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) , ( ( 𝑅 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝐿 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝑅 ) } ) ) ⟩ ) = ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) )
29	14 28	eqtrdi	⊢ ( 𝐼 ∈ ω → ( 1st ‘ ( 𝐹 ‘ suc 𝐼 ) ) = ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) )
30	12 29	eqtrd	⊢ ( 𝐼 ∈ ω → ( ( 1st ∘ 𝐹 ) ‘ suc 𝐼 ) = ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) )
31	4 30	eqtrid	⊢ ( 𝐼 ∈ ω → ( 𝐿 ‘ suc 𝐼 ) = ( ( 𝐿 ‘ 𝐼 ) ∪ ( { 𝑎 ∣ ∃ 𝑥𝑅 ∈ ( R ‘ 𝐴 ) ∃ 𝑦𝐿 ∈ ( 𝐿 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝑅 -s 𝐴 ) ·s 𝑦𝐿 ) ) /su 𝑥𝑅 ) } ∪ { 𝑎 ∣ ∃ 𝑥𝐿 ∈ { 𝑥 ∈ ( L ‘ 𝐴 ) ∣ 0s <s 𝑥 } ∃ 𝑦𝑅 ∈ ( 𝑅 ‘ 𝐼 ) 𝑎 = ( ( 1s +s ( ( 𝑥𝐿 -s 𝐴 ) ·s 𝑦𝑅 ) ) /su 𝑥𝐿 ) } ) ) )