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Theorem zmulscld 28408
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 28395 . . 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 28395 . . 3 (𝐵 ∈ ℤs ↔ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
64, 5sylib 218 . 2 (𝜑 → ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
7 reeanv 3210 . . . . 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 3114 . . . 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 3210 . . . 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 nnno 28335 . . . . . . . . . . 11 (𝑥 ∈ ℕs𝑥 No )
1211ad2antrr 727 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑥 No )
13 nnno 28335 . . . . . . . . . . 11 (𝑦 ∈ ℕs𝑦 No )
1413ad2antrl 729 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑦 No )
1512, 14subscld 28074 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 -s 𝑦) ∈ No )
16 nnno 28335 . . . . . . . . . 10 (𝑧 ∈ ℕs𝑧 No )
1716ad2antlr 728 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑧 No )
18 nnno 28335 . . . . . . . . . 10 (𝑤 ∈ ℕs𝑤 No )
1918ad2antll 730 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑤 No )
2015, 17, 19subsdid 28169 . . . . . . . 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 28358 . . . . . . . . . . . . 13 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (𝑥 ·s 𝑧) ∈ ℕs)
2221adantr 480 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ ℕs)
2322nnnod 28337 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ No )
24 simprl 771 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑦 ∈ ℕs)
25 simplr 769 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑧 ∈ ℕs)
26 nnmulscl 28358 . . . . . . . . . . . . 13 ((𝑦 ∈ ℕs𝑧 ∈ ℕs) → (𝑦 ·s 𝑧) ∈ ℕs)
2724, 25, 26syl2anc 585 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ ℕs)
2827nnnod 28337 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ No )
2923, 28subscld 28074 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) ∈ No )
30 nnmulscl 28358 . . . . . . . . . . . 12 ((𝑥 ∈ ℕs𝑤 ∈ ℕs) → (𝑥 ·s 𝑤) ∈ ℕs)
3130ad2ant2rl 750 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ ℕs)
3231nnnod 28337 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ No )
33 nnmulscl 28358 . . . . . . . . . . . 12 ((𝑦 ∈ ℕs𝑤 ∈ ℕs) → (𝑦 ·s 𝑤) ∈ ℕs)
3433adantl 481 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ ℕs)
3534nnnod 28337 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ No )
3629, 32, 35subsubs2d 28106 . . . . . . . . 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 28170 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑧) = ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)))
3812, 14, 19subsdird 28170 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑤) = ((𝑥 ·s 𝑤) -s (𝑦 ·s 𝑤)))
3937, 38oveq12d 7386 . . . . . . . . 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 28112 . . . . . . . . 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 2782 . . . . . . . 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 2772 . . . . . . 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 28357 . . . . . . . . . 10 (((𝑥 ·s 𝑧) ∈ ℕs ∧ (𝑦 ·s 𝑤) ∈ ℕs) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
4422, 34, 43syl2anc 585 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
45 nnaddscl 28357 . . . . . . . . . 10 (((𝑦 ·s 𝑧) ∈ ℕs ∧ (𝑥 ·s 𝑤) ∈ ℕs) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
4627, 31, 45syl2anc 585 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
47 eqid 2737 . . . . . . . . . 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 7417 . . . . . . . . . 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 1453 . . . . . . . . 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 585 . . . . . . . 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 28395 . . . . . . . 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 2837 . . . . . 6 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) ∈ ℤs)
54 oveq12 7377 . . . . . . 7 ((𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) = ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)))
5554eleq1d 2822 . . . . . 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 3195 . . . 4 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (∃𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5857rexlimivv 3180 . . 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 585 1 (𝜑 → (𝐴 ·s 𝐵) ∈ ℤs)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 395   = wceq 1542  wcel 2114  wrex 3062  (class class class)co 7368   No csur 27622   +s cadds 27970   -s csubs 28031   ·s cmuls 28117  scnns 28324  sczs 28389
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1969  ax-7 2010  ax-8 2116  ax-9 2124  ax-10 2147  ax-11 2163  ax-12 2185  ax-ext 2709  ax-rep 5226  ax-sep 5243  ax-nul 5253  ax-pow 5312  ax-pr 5379  ax-un 7690
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-3or 1088  df-3an 1089  df-tru 1545  df-fal 1555  df-ex 1782  df-nf 1786  df-sb 2069  df-mo 2540  df-eu 2570  df-clab 2716  df-cleq 2729  df-clel 2812  df-nfc 2886  df-ne 2934  df-ral 3053  df-rex 3063  df-rmo 3352  df-reu 3353  df-rab 3402  df-v 3444  df-sbc 3743  df-csb 3852  df-dif 3906  df-un 3908  df-in 3910  df-ss 3920  df-pss 3923  df-nul 4288  df-if 4482  df-pw 4558  df-sn 4583  df-pr 4585  df-tp 4587  df-op 4589  df-ot 4591  df-uni 4866  df-int 4905  df-iun 4950  df-br 5101  df-opab 5163  df-mpt 5182  df-tr 5208  df-id 5527  df-eprel 5532  df-po 5540  df-so 5541  df-fr 5585  df-se 5586  df-we 5587  df-xp 5638  df-rel 5639  df-cnv 5640  df-co 5641  df-dm 5642  df-rn 5643  df-res 5644  df-ima 5645  df-pred 6267  df-ord 6328  df-on 6329  df-lim 6330  df-suc 6331  df-iota 6456  df-fun 6502  df-fn 6503  df-f 6504  df-f1 6505  df-fo 6506  df-f1o 6507  df-fv 6508  df-riota 7325  df-ov 7371  df-oprab 7372  df-mpo 7373  df-om 7819  df-1st 7943  df-2nd 7944  df-frecs 8233  df-wrecs 8264  df-recs 8313  df-rdg 8351  df-1o 8407  df-2o 8408  df-nadd 8604  df-no 27625  df-lts 27626  df-bday 27627  df-les 27728  df-slts 27769  df-cuts 27771  df-0s 27818  df-1s 27819  df-made 27838  df-old 27839  df-left 27841  df-right 27842  df-norec 27949  df-norec2 27960  df-adds 27971  df-negs 28032  df-subs 28033  df-muls 28118  df-n0s 28325  df-nns 28326  df-zs 28390
This theorem is referenced by:  zsoring  28420  zexpscl  28445  pw2cutp1  28472  z12addscl  28488
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