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Theorem zmulscld 28290
Description: The surreal integers are closed under multiplication. (Contributed by Scott Fenton, 20-Aug-2025.)
Hypotheses
Ref Expression
zmulscld.1 (𝜑𝐴 ∈ ℤs)
zmulscld.2 (𝜑𝐵 ∈ ℤs)
Assertion
Ref Expression
zmulscld (𝜑 → (𝐴 ·s 𝐵) ∈ ℤs)

Proof of Theorem zmulscld
Dummy variables 𝑥 𝑦 𝑧 𝑤 𝑡 𝑢 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 zmulscld.1 . . 3 (𝜑𝐴 ∈ ℤs)
2 elzs 28277 . . 3 (𝐴 ∈ ℤs ↔ ∃𝑥 ∈ ℕs𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦))
31, 2sylib 218 . 2 (𝜑 → ∃𝑥 ∈ ℕs𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦))
4 zmulscld.2 . . 3 (𝜑𝐵 ∈ ℤs)
5 elzs 28277 . . 3 (𝐵 ∈ ℤs ↔ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
64, 5sylib 218 . 2 (𝜑 → ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
7 reeanv 3201 . . . . 5 (∃𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) ↔ (∃𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)))
872rexbii 3105 . . . 4 (∃𝑥 ∈ ℕs𝑧 ∈ ℕs𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) ↔ ∃𝑥 ∈ ℕs𝑧 ∈ ℕs (∃𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)))
9 reeanv 3201 . . . 4 (∃𝑥 ∈ ℕs𝑧 ∈ ℕs (∃𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)) ↔ (∃𝑥 ∈ ℕs𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)))
108, 9bitri 275 . . 3 (∃𝑥 ∈ ℕs𝑧 ∈ ℕs𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) ↔ (∃𝑥 ∈ ℕs𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)))
11 nnsno 28222 . . . . . . . . . . 11 (𝑥 ∈ ℕs𝑥 No )
1211ad2antrr 726 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑥 No )
13 nnsno 28222 . . . . . . . . . . 11 (𝑦 ∈ ℕs𝑦 No )
1413ad2antrl 728 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑦 No )
1512, 14subscld 27972 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 -s 𝑦) ∈ No )
16 nnsno 28222 . . . . . . . . . 10 (𝑧 ∈ ℕs𝑧 No )
1716ad2antlr 727 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑧 No )
18 nnsno 28222 . . . . . . . . . 10 (𝑤 ∈ ℕs𝑤 No )
1918ad2antll 729 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑤 No )
2015, 17, 19subsdid 28066 . . . . . . . 8 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) = (((𝑥 -s 𝑦) ·s 𝑧) -s ((𝑥 -s 𝑦) ·s 𝑤)))
21 nnmulscl 28244 . . . . . . . . . . . . 13 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (𝑥 ·s 𝑧) ∈ ℕs)
2221adantr 480 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ ℕs)
2322nnsnod 28224 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ No )
24 simprl 770 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑦 ∈ ℕs)
25 simplr 768 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑧 ∈ ℕs)
26 nnmulscl 28244 . . . . . . . . . . . . 13 ((𝑦 ∈ ℕs𝑧 ∈ ℕs) → (𝑦 ·s 𝑧) ∈ ℕs)
2724, 25, 26syl2anc 584 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ ℕs)
2827nnsnod 28224 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ No )
2923, 28subscld 27972 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) ∈ No )
30 nnmulscl 28244 . . . . . . . . . . . 12 ((𝑥 ∈ ℕs𝑤 ∈ ℕs) → (𝑥 ·s 𝑤) ∈ ℕs)
3130ad2ant2rl 749 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ ℕs)
3231nnsnod 28224 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ No )
33 nnmulscl 28244 . . . . . . . . . . . 12 ((𝑦 ∈ ℕs𝑤 ∈ ℕs) → (𝑦 ·s 𝑤) ∈ ℕs)
3433adantl 481 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ ℕs)
3534nnsnod 28224 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ No )
3629, 32, 35subsubs2d 28004 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) -s ((𝑥 ·s 𝑤) -s (𝑦 ·s 𝑤))) = (((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) +s ((𝑦 ·s 𝑤) -s (𝑥 ·s 𝑤))))
3712, 14, 17subsdird 28067 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑧) = ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)))
3812, 14, 19subsdird 28067 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑤) = ((𝑥 ·s 𝑤) -s (𝑦 ·s 𝑤)))
3937, 38oveq12d 7367 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (((𝑥 -s 𝑦) ·s 𝑧) -s ((𝑥 -s 𝑦) ·s 𝑤)) = (((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) -s ((𝑥 ·s 𝑤) -s (𝑦 ·s 𝑤))))
4023, 35, 28, 32addsubs4d 28009 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) +s ((𝑦 ·s 𝑤) -s (𝑥 ·s 𝑤))))
4136, 39, 403eqtr4d 2774 . . . . . . . 8 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (((𝑥 -s 𝑦) ·s 𝑧) -s ((𝑥 -s 𝑦) ·s 𝑤)) = (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))))
4220, 41eqtrd 2764 . . . . . . 7 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) = (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))))
43 nnaddscl 28243 . . . . . . . . . 10 (((𝑥 ·s 𝑧) ∈ ℕs ∧ (𝑦 ·s 𝑤) ∈ ℕs) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
4422, 34, 43syl2anc 584 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
45 nnaddscl 28243 . . . . . . . . . 10 (((𝑦 ·s 𝑧) ∈ ℕs ∧ (𝑥 ·s 𝑤) ∈ ℕs) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
4627, 31, 45syl2anc 584 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
47 eqid 2729 . . . . . . . . . 10 (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)))
48 rspceov 7398 . . . . . . . . . 10 ((((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs ∧ ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs ∧ (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)))) → ∃𝑡 ∈ ℕs𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 -s 𝑢))
4947, 48mp3an3 1452 . . . . . . . . 9 ((((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs ∧ ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs) → ∃𝑡 ∈ ℕs𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 -s 𝑢))
5044, 46, 49syl2anc 584 . . . . . . . 8 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ∃𝑡 ∈ ℕs𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 -s 𝑢))
51 elzs 28277 . . . . . . . 8 ((((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) ∈ ℤs ↔ ∃𝑡 ∈ ℕs𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 -s 𝑢))
5250, 51sylibr 234 . . . . . . 7 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) -s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) ∈ ℤs)
5342, 52eqeltrd 2828 . . . . . 6 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) ∈ ℤs)
54 oveq12 7358 . . . . . . 7 ((𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) = ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)))
5554eleq1d 2813 . . . . . 6 ((𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → ((𝐴 ·s 𝐵) ∈ ℤs ↔ ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) ∈ ℤs))
5653, 55syl5ibrcom 247 . . . . 5 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5756rexlimdvva 3186 . . . 4 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (∃𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5857rexlimivv 3171 . . 3 (∃𝑥 ∈ ℕs𝑧 ∈ ℕs𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs)
5910, 58sylbir 235 . 2 ((∃𝑥 ∈ ℕs𝑦 ∈ ℕs 𝐴 = (𝑥 -s 𝑦) ∧ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs)
603, 6, 59syl2anc 584 1 (𝜑 → (𝐴 ·s 𝐵) ∈ ℤs)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 395   = wceq 1540  wcel 2109  wrex 3053  (class class class)co 7349   No csur 27549   +s cadds 27871   -s csubs 27931   ·s cmuls 28014  scnns 28212  sczs 28271
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-8 2111  ax-9 2119  ax-10 2142  ax-11 2158  ax-12 2178  ax-ext 2701  ax-rep 5218  ax-sep 5235  ax-nul 5245  ax-pow 5304  ax-pr 5371  ax-un 7671
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-nf 1784  df-sb 2066  df-mo 2533  df-eu 2562  df-clab 2708  df-cleq 2721  df-clel 2803  df-nfc 2878  df-ne 2926  df-ral 3045  df-rex 3054  df-rmo 3343  df-reu 3344  df-rab 3395  df-v 3438  df-sbc 3743  df-csb 3852  df-dif 3906  df-un 3908  df-in 3910  df-ss 3920  df-pss 3923  df-nul 4285  df-if 4477  df-pw 4553  df-sn 4578  df-pr 4580  df-tp 4582  df-op 4584  df-ot 4586  df-uni 4859  df-int 4897  df-iun 4943  df-br 5093  df-opab 5155  df-mpt 5174  df-tr 5200  df-id 5514  df-eprel 5519  df-po 5527  df-so 5528  df-fr 5572  df-se 5573  df-we 5574  df-xp 5625  df-rel 5626  df-cnv 5627  df-co 5628  df-dm 5629  df-rn 5630  df-res 5631  df-ima 5632  df-pred 6249  df-ord 6310  df-on 6311  df-lim 6312  df-suc 6313  df-iota 6438  df-fun 6484  df-fn 6485  df-f 6486  df-f1 6487  df-fo 6488  df-f1o 6489  df-fv 6490  df-riota 7306  df-ov 7352  df-oprab 7353  df-mpo 7354  df-om 7800  df-1st 7924  df-2nd 7925  df-frecs 8214  df-wrecs 8245  df-recs 8294  df-rdg 8332  df-1o 8388  df-2o 8389  df-nadd 8584  df-no 27552  df-slt 27553  df-bday 27554  df-sle 27655  df-sslt 27692  df-scut 27694  df-0s 27738  df-1s 27739  df-made 27757  df-old 27758  df-left 27760  df-right 27761  df-norec 27850  df-norec2 27861  df-adds 27872  df-negs 27932  df-subs 27933  df-muls 28015  df-n0s 28213  df-nns 28214  df-zs 28272
This theorem is referenced by:  zsoring  28301  zexpscl  28326  pw2cutp1  28349  zs12addscl  28354  zs12bday  28361
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