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 Description: Addition cancellation law for positive reals. Proposition 9-3.5(vi) of [Gleason] p. 123. (Contributed by NM, 9-Apr-1996.) (New usage is discouraged.)
Assertion
Ref Expression
addcanpr ((𝐴P𝐵P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → 𝐵 = 𝐶))

StepHypRef Expression
1 addclpr 10418 . . . 4 ((𝐴P𝐵P) → (𝐴 +P 𝐵) ∈ P)
2 eleq1 2898 . . . . 5 ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → ((𝐴 +P 𝐵) ∈ P ↔ (𝐴 +P 𝐶) ∈ P))
3 dmplp 10412 . . . . . 6 dom +P = (P × P)
4 0npr 10392 . . . . . 6 ¬ ∅ ∈ P
53, 4ndmovrcl 7312 . . . . 5 ((𝐴 +P 𝐶) ∈ P → (𝐴P𝐶P))
62, 5syl6bi 255 . . . 4 ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → ((𝐴 +P 𝐵) ∈ P → (𝐴P𝐶P)))
71, 6syl5com 31 . . 3 ((𝐴P𝐵P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → (𝐴P𝐶P)))
8 ltapr 10445 . . . . . . . 8 (𝐴P → (𝐵<P 𝐶 ↔ (𝐴 +P 𝐵)<P (𝐴 +P 𝐶)))
9 ltapr 10445 . . . . . . . 8 (𝐴P → (𝐶<P 𝐵 ↔ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵)))
108, 9orbi12d 915 . . . . . . 7 (𝐴P → ((𝐵<P 𝐶𝐶<P 𝐵) ↔ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
1110notbid 320 . . . . . 6 (𝐴P → (¬ (𝐵<P 𝐶𝐶<P 𝐵) ↔ ¬ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
1211ad2antrr 724 . . . . 5 (((𝐴P𝐵P) ∧ (𝐴P𝐶P)) → (¬ (𝐵<P 𝐶𝐶<P 𝐵) ↔ ¬ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
13 ltsopr 10432 . . . . . . 7 <P Or P
14 sotrieq 5478 . . . . . . 7 ((<P Or P ∧ (𝐵P𝐶P)) → (𝐵 = 𝐶 ↔ ¬ (𝐵<P 𝐶𝐶<P 𝐵)))
1513, 14mpan 688 . . . . . 6 ((𝐵P𝐶P) → (𝐵 = 𝐶 ↔ ¬ (𝐵<P 𝐶𝐶<P 𝐵)))
1615ad2ant2l 744 . . . . 5 (((𝐴P𝐵P) ∧ (𝐴P𝐶P)) → (𝐵 = 𝐶 ↔ ¬ (𝐵<P 𝐶𝐶<P 𝐵)))
17 addclpr 10418 . . . . . 6 ((𝐴P𝐶P) → (𝐴 +P 𝐶) ∈ P)
18 sotrieq 5478 . . . . . . 7 ((<P Or P ∧ ((𝐴 +P 𝐵) ∈ P ∧ (𝐴 +P 𝐶) ∈ P)) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) ↔ ¬ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
1913, 18mpan 688 . . . . . 6 (((𝐴 +P 𝐵) ∈ P ∧ (𝐴 +P 𝐶) ∈ P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) ↔ ¬ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
201, 17, 19syl2an 597 . . . . 5 (((𝐴P𝐵P) ∧ (𝐴P𝐶P)) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) ↔ ¬ ((𝐴 +P 𝐵)<P (𝐴 +P 𝐶) ∨ (𝐴 +P 𝐶)<P (𝐴 +P 𝐵))))
2112, 16, 203bitr4d 313 . . . 4 (((𝐴P𝐵P) ∧ (𝐴P𝐶P)) → (𝐵 = 𝐶 ↔ (𝐴 +P 𝐵) = (𝐴 +P 𝐶)))
2221exbiri 809 . . 3 ((𝐴P𝐵P) → ((𝐴P𝐶P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → 𝐵 = 𝐶)))
237, 22syld 47 . 2 ((𝐴P𝐵P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → 𝐵 = 𝐶)))
2423pm2.43d 53 1 ((𝐴P𝐵P) → ((𝐴 +P 𝐵) = (𝐴 +P 𝐶) → 𝐵 = 𝐶))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 208   ∧ wa 398   ∨ wo 843   = wceq 1537   ∈ wcel 2114   class class class wbr 5042   Or wor 5449  (class class class)co 7133  Pcnp 10259   +P cpp 10261
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