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Theorem ltexprlem3 9845
 Description: Lemma for Proposition 9-3.5(iv) of [Gleason] p. 123. (Contributed by NM, 6-Apr-1996.) (New usage is discouraged.)
Hypothesis
Ref Expression
ltexprlem.1 𝐶 = {𝑥 ∣ ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵)}
Assertion
Ref Expression
ltexprlem3 (𝐵P → (𝑥𝐶 → ∀𝑧(𝑧 <Q 𝑥𝑧𝐶)))
Distinct variable groups:   𝑥,𝑦,𝑧,𝐴   𝑥,𝐵,𝑦,𝑧   𝑥,𝐶,𝑧
Allowed substitution hint:   𝐶(𝑦)

Proof of Theorem ltexprlem3
StepHypRef Expression
1 elprnq 9798 . . . . . . . . . 10 ((𝐵P ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → (𝑦 +Q 𝑥) ∈ Q)
2 addnqf 9755 . . . . . . . . . . . . 13 +Q :(Q × Q)⟶Q
32fdmi 6039 . . . . . . . . . . . 12 dom +Q = (Q × Q)
4 0nnq 9731 . . . . . . . . . . . 12 ¬ ∅ ∈ Q
53, 4ndmovrcl 6805 . . . . . . . . . . 11 ((𝑦 +Q 𝑥) ∈ Q → (𝑦Q𝑥Q))
65simpld 475 . . . . . . . . . 10 ((𝑦 +Q 𝑥) ∈ Q𝑦Q)
7 ltanq 9778 . . . . . . . . . 10 (𝑦Q → (𝑧 <Q 𝑥 ↔ (𝑦 +Q 𝑧) <Q (𝑦 +Q 𝑥)))
81, 6, 73syl 18 . . . . . . . . 9 ((𝐵P ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → (𝑧 <Q 𝑥 ↔ (𝑦 +Q 𝑧) <Q (𝑦 +Q 𝑥)))
9 prcdnq 9800 . . . . . . . . 9 ((𝐵P ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → ((𝑦 +Q 𝑧) <Q (𝑦 +Q 𝑥) → (𝑦 +Q 𝑧) ∈ 𝐵))
108, 9sylbid 230 . . . . . . . 8 ((𝐵P ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → (𝑧 <Q 𝑥 → (𝑦 +Q 𝑧) ∈ 𝐵))
1110impancom 456 . . . . . . 7 ((𝐵P𝑧 <Q 𝑥) → ((𝑦 +Q 𝑥) ∈ 𝐵 → (𝑦 +Q 𝑧) ∈ 𝐵))
1211anim2d 588 . . . . . 6 ((𝐵P𝑧 <Q 𝑥) → ((¬ 𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → (¬ 𝑦𝐴 ∧ (𝑦 +Q 𝑧) ∈ 𝐵)))
1312eximdv 1844 . . . . 5 ((𝐵P𝑧 <Q 𝑥) → (∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵) → ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑧) ∈ 𝐵)))
14 ltexprlem.1 . . . . . 6 𝐶 = {𝑥 ∣ ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵)}
1514abeq2i 2733 . . . . 5 (𝑥𝐶 ↔ ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵))
16 vex 3198 . . . . . 6 𝑧 ∈ V
17 oveq2 6643 . . . . . . . . 9 (𝑥 = 𝑧 → (𝑦 +Q 𝑥) = (𝑦 +Q 𝑧))
1817eleq1d 2684 . . . . . . . 8 (𝑥 = 𝑧 → ((𝑦 +Q 𝑥) ∈ 𝐵 ↔ (𝑦 +Q 𝑧) ∈ 𝐵))
1918anbi2d 739 . . . . . . 7 (𝑥 = 𝑧 → ((¬ 𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵) ↔ (¬ 𝑦𝐴 ∧ (𝑦 +Q 𝑧) ∈ 𝐵)))
2019exbidv 1848 . . . . . 6 (𝑥 = 𝑧 → (∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑥) ∈ 𝐵) ↔ ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑧) ∈ 𝐵)))
2116, 20, 14elab2 3348 . . . . 5 (𝑧𝐶 ↔ ∃𝑦𝑦𝐴 ∧ (𝑦 +Q 𝑧) ∈ 𝐵))
2213, 15, 213imtr4g 285 . . . 4 ((𝐵P𝑧 <Q 𝑥) → (𝑥𝐶𝑧𝐶))
2322ex 450 . . 3 (𝐵P → (𝑧 <Q 𝑥 → (𝑥𝐶𝑧𝐶)))
2423com23 86 . 2 (𝐵P → (𝑥𝐶 → (𝑧 <Q 𝑥𝑧𝐶)))
2524alrimdv 1855 1 (𝐵P → (𝑥𝐶 → ∀𝑧(𝑧 <Q 𝑥𝑧𝐶)))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 384  ∀wal 1479   = wceq 1481  ∃wex 1702   ∈ wcel 1988  {cab 2606   class class class wbr 4644   × cxp 5102  (class class class)co 6635  Qcnq 9659   +Q cplq 9662
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