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Theorem zmulscld 28321
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 28308 . . 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 28308 . . 3 (𝐵 ∈ ℤs ↔ ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
64, 5sylib 218 . 2 (𝜑 → ∃𝑧 ∈ ℕs𝑤 ∈ ℕs 𝐵 = (𝑧 -s 𝑤))
7 reeanv 3204 . . . . 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 3108 . . . 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 3204 . . . 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 28253 . . . . . . . . . . 11 (𝑥 ∈ ℕs𝑥 No )
1211ad2antrr 726 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑥 No )
13 nnsno 28253 . . . . . . . . . . 11 (𝑦 ∈ ℕs𝑦 No )
1413ad2antrl 728 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑦 No )
1512, 14subscld 28003 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 -s 𝑦) ∈ No )
16 nnsno 28253 . . . . . . . . . 10 (𝑧 ∈ ℕs𝑧 No )
1716ad2antlr 727 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑧 No )
18 nnsno 28253 . . . . . . . . . 10 (𝑤 ∈ ℕs𝑤 No )
1918ad2antll 729 . . . . . . . . 9 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → 𝑤 No )
2015, 17, 19subsdid 28097 . . . . . . . 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 28275 . . . . . . . . . . . . 13 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (𝑥 ·s 𝑧) ∈ ℕs)
2221adantr 480 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ ℕs)
2322nnsnod 28255 . . . . . . . . . . 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 28275 . . . . . . . . . . . . 13 ((𝑦 ∈ ℕs𝑧 ∈ ℕs) → (𝑦 ·s 𝑧) ∈ ℕs)
2724, 25, 26syl2anc 584 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ ℕs)
2827nnsnod 28255 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ No )
2923, 28subscld 28003 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)) ∈ No )
30 nnmulscl 28275 . . . . . . . . . . . 12 ((𝑥 ∈ ℕs𝑤 ∈ ℕs) → (𝑥 ·s 𝑤) ∈ ℕs)
3130ad2ant2rl 749 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ ℕs)
3231nnsnod 28255 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ No )
33 nnmulscl 28275 . . . . . . . . . . . 12 ((𝑦 ∈ ℕs𝑤 ∈ ℕs) → (𝑦 ·s 𝑤) ∈ ℕs)
3433adantl 481 . . . . . . . . . . 11 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ ℕs)
3534nnsnod 28255 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ No )
3629, 32, 35subsubs2d 28035 . . . . . . . . 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 28098 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑧) = ((𝑥 ·s 𝑧) -s (𝑦 ·s 𝑧)))
3812, 14, 19subsdird 28098 . . . . . . . . . 10 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s 𝑤) = ((𝑥 ·s 𝑤) -s (𝑦 ·s 𝑤)))
3937, 38oveq12d 7364 . . . . . . . . 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 28040 . . . . . . . . 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 2776 . . . . . . . 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 2766 . . . . . . 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 28274 . . . . . . . . . 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 28274 . . . . . . . . . 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 2731 . . . . . . . . . 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 7395 . . . . . . . . . 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 28308 . . . . . . . 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 2831 . . . . . 6 (((𝑥 ∈ ℕs𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs𝑤 ∈ ℕs)) → ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)) ∈ ℤs)
54 oveq12 7355 . . . . . . 7 ((𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) = ((𝑥 -s 𝑦) ·s (𝑧 -s 𝑤)))
5554eleq1d 2816 . . . . . 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 3189 . . . 4 ((𝑥 ∈ ℕs𝑧 ∈ ℕs) → (∃𝑦 ∈ ℕs𝑤 ∈ ℕs (𝐴 = (𝑥 -s 𝑦) ∧ 𝐵 = (𝑧 -s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5857rexlimivv 3174 . . 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 1541  wcel 2111  wrex 3056  (class class class)co 7346   No csur 27578   +s cadds 27902   -s csubs 27962   ·s cmuls 28045  scnns 28243  sczs 28302
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2113  ax-9 2121  ax-10 2144  ax-11 2160  ax-12 2180  ax-ext 2703  ax-rep 5215  ax-sep 5232  ax-nul 5242  ax-pow 5301  ax-pr 5368  ax-un 7668
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1544  df-fal 1554  df-ex 1781  df-nf 1785  df-sb 2068  df-mo 2535  df-eu 2564  df-clab 2710  df-cleq 2723  df-clel 2806  df-nfc 2881  df-ne 2929  df-ral 3048  df-rex 3057  df-rmo 3346  df-reu 3347  df-rab 3396  df-v 3438  df-sbc 3737  df-csb 3846  df-dif 3900  df-un 3902  df-in 3904  df-ss 3914  df-pss 3917  df-nul 4281  df-if 4473  df-pw 4549  df-sn 4574  df-pr 4576  df-tp 4578  df-op 4580  df-ot 4582  df-uni 4857  df-int 4896  df-iun 4941  df-br 5090  df-opab 5152  df-mpt 5171  df-tr 5197  df-id 5509  df-eprel 5514  df-po 5522  df-so 5523  df-fr 5567  df-se 5568  df-we 5569  df-xp 5620  df-rel 5621  df-cnv 5622  df-co 5623  df-dm 5624  df-rn 5625  df-res 5626  df-ima 5627  df-pred 6248  df-ord 6309  df-on 6310  df-lim 6311  df-suc 6312  df-iota 6437  df-fun 6483  df-fn 6484  df-f 6485  df-f1 6486  df-fo 6487  df-f1o 6488  df-fv 6489  df-riota 7303  df-ov 7349  df-oprab 7350  df-mpo 7351  df-om 7797  df-1st 7921  df-2nd 7922  df-frecs 8211  df-wrecs 8242  df-recs 8291  df-rdg 8329  df-1o 8385  df-2o 8386  df-nadd 8581  df-no 27581  df-slt 27582  df-bday 27583  df-sle 27684  df-sslt 27721  df-scut 27723  df-0s 27768  df-1s 27769  df-made 27788  df-old 27789  df-left 27791  df-right 27792  df-norec 27881  df-norec2 27892  df-adds 27903  df-negs 27963  df-subs 27964  df-muls 28046  df-n0s 28244  df-nns 28245  df-zs 28303
This theorem is referenced by:  zsoring  28332  zexpscl  28357  pw2cutp1  28381  zs12addscl  28387  zs12bday  28394
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