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Theorem zmulscld 28798
Description: The surreal integers are closed under multiplication. (Contributed by Scott Fenton, 20-Aug-2025.)
Hypotheses
Ref Expression
zmulscld.1 (𝜑 → 𝐴 ∈ ℤs)
zmulscld.2 (𝜑 → 𝐵 ∈ 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 (𝜑 → 𝐴 ∈ ℤs)
2 elzs 28785 . . 3 (𝐴 ∈ ℤs ↔ ∃𝑥 ∈ ℕs ∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦))
31, 2sylib 221 . 2 (𝜑 → ∃𝑥 ∈ ℕs ∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦))
4 zmulscld.2 . . 3 (𝜑 → 𝐵 ∈ ℤs)
5 elzs 28785 . . 3 (𝐵 ∈ ℤs ↔ ∃𝑧 ∈ ℕs ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤))
64, 5sylib 221 . 2 (𝜑 → ∃𝑧 ∈ ℕs ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤))
7 reeanv 3238 . . . . 5 (∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) ↔ (∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)))
872rexbii 3142 . . . 4 (∃𝑥 ∈ ℕs ∃𝑧 ∈ ℕs ∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) ↔ ∃𝑥 ∈ ℕs ∃𝑧 ∈ ℕs (∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)))
9 reeanv 3238 . . . 4 (∃𝑥 ∈ ℕs ∃𝑧 ∈ ℕs (∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)) ↔ (∃𝑥 ∈ ℕs ∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑧 ∈ ℕs ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)))
108, 9bitri 278 . . 3 (∃𝑥 ∈ ℕs ∃𝑧 ∈ ℕs ∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) ↔ (∃𝑥 ∈ ℕs ∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑧 ∈ ℕs ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)))
11 nnno 28725 . . . . . . . . . . 11 (𝑥 ∈ ℕs → 𝑥 ∈ No)
1211ad2antrr 739 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑥 ∈ No)
13 nnno 28725 . . . . . . . . . . 11 (𝑦 ∈ ℕs → 𝑦 ∈ No)
1413ad2antrl 741 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑦 ∈ No)
1512, 14subscld 28464 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 −s 𝑦) ∈ No)
16 nnno 28725 . . . . . . . . . 10 (𝑧 ∈ ℕs → 𝑧 ∈ No)
1716ad2antlr 740 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑧 ∈ No)
18 nnno 28725 . . . . . . . . . 10 (𝑤 ∈ ℕs → 𝑤 ∈ No)
1918ad2antll 742 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑤 ∈ No)
2015, 17, 19subsdid 28559 . . . . . . . 8 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)) = (((𝑥 −s 𝑦) ·s 𝑧) −s ((𝑥 −s 𝑦) ·s 𝑤)))
21 nnmulscl 28748 . . . . . . . . . . . . 13 ((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) → (𝑥 ·s 𝑧) ∈ ℕs)
2221adantr 486 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ ℕs)
2322nnnod 28727 . . . . . . . . . . 11 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 ·s 𝑧) ∈ No)
24 simprl 783 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑦 ∈ ℕs)
25 simplr 781 . . . . . . . . . . . . 13 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑧 ∈ ℕs)
26 nnmulscl 28748 . . . . . . . . . . . . 13 ((𝑦 ∈ ℕs ∧ 𝑧 ∈ ℕs) → (𝑦 ·s 𝑧) ∈ ℕs)
2724, 25, 26syl2anc 596 . . . . . . . . . . . 12 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ ℕs)
2827nnnod 28727 . . . . . . . . . . 11 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ No)
2923, 28subscld 28464 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) −s (𝑦 ·s 𝑧)) ∈ No)
30 nnmulscl 28748 . . . . . . . . . . . 12 ((𝑥 ∈ ℕs ∧ 𝑤 ∈ ℕs) → (𝑥 ·s 𝑤) ∈ ℕs)
3130ad2ant2rl 762 . . . . . . . . . . 11 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ ℕs)
3231nnnod 28727 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ No)
33 nnmulscl 28748 . . . . . . . . . . . 12 ((𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs) → (𝑦 ·s 𝑤) ∈ ℕs)
3433adantl 487 . . . . . . . . . . 11 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ ℕs)
3534nnnod 28727 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ No)
3629, 32, 35subsubs2d 28496 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ 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 28560 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s 𝑧) = ((𝑥 ·s 𝑧) −s (𝑦 ·s 𝑧)))
3812, 14, 19subsdird 28560 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s 𝑤) = ((𝑥 ·s 𝑤) −s (𝑦 ·s 𝑤)))
3937, 38oveq12d 7448 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ 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 28502 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ 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 2808 . . . . . . . 8 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ 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 2798 . . . . . . 7 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ 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 28747 . . . . . . . . . 10 (((𝑥 ·s 𝑧) ∈ ℕs ∧ (𝑦 ·s 𝑤) ∈ ℕs) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
4422, 34, 43syl2anc 596 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs)
45 nnaddscl 28747 . . . . . . . . . 10 (((𝑦 ·s 𝑧) ∈ ℕs ∧ (𝑥 ·s 𝑤) ∈ ℕs) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
4627, 31, 45syl2anc 596 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs)
47 eqid 2763 . . . . . . . . . 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 7479 . . . . . . . . . 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 ∈ ℕs ∃𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 −s 𝑢))
4947, 48mp3an3 1479 . . . . . . . . 9 ((((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) ∈ ℕs ∧ ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤)) ∈ ℕs) → ∃𝑡 ∈ ℕs ∃𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 −s 𝑢))
5044, 46, 49syl2anc 596 . . . . . . . 8 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ∃𝑡 ∈ ℕs ∃𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 −s 𝑢))
51 elzs 28785 . . . . . . . 8 ((((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) ∈ ℤs ↔ ∃𝑡 ∈ ℕs ∃𝑢 ∈ ℕs (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) = (𝑡 −s 𝑢))
5250, 51sylibr 237 . . . . . . 7 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (((𝑥 ·s 𝑧) +s (𝑦 ·s 𝑤)) −s ((𝑦 ·s 𝑧) +s (𝑥 ·s 𝑤))) ∈ ℤs)
5342, 52eqeltrd 2864 . . . . . 6 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)) ∈ ℤs)
54 oveq12 7439 . . . . . . 7 ((𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) = ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)))
5554eleq1d 2849 . . . . . 6 ((𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → ((𝐴 ·s 𝐵) ∈ ℤs ↔ ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)) ∈ ℤs))
5653, 55syl5ibrcom 250 . . . . 5 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5756rexlimdvva 3223 . . . 4 ((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) → (∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5857rexlimivv 3208 . . 3 (∃𝑥 ∈ ℕs ∃𝑧 ∈ ℕs ∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs)
5910, 58sylbir 238 . 2 ((∃𝑥 ∈ ℕs ∃𝑦 ∈ ℕs 𝐴 = (𝑥 −s 𝑦) ∧ ∃𝑧 ∈ ℕs ∃𝑤 ∈ ℕs 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs)
603, 6, 59syl2anc 596 1 (𝜑 → (𝐴 ·s 𝐵) ∈ ℤs)
Colors of variables:    wff setvar class
This proof depends on syntax axioms:   → wi 4   ∧ wa 401   = wceq 1569   ∈ wcel 2146  ∃wrex 3090  (class class class)co 7430  Nocsur 28012   +s cadds 28360   −s csubs 28421   ·s cmuls 28507  ℕscnns 28714  ℤsczs 28779
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1944  ax-6 2001  ax-7 2042  ax-8 2148  ax-9 2156  ax-10 2179  ax-11 2196  ax-12 2215  ax-ext 2735  ax-rep 5235  ax-sep 5252  ax-nul 5263  ax-pow 5331  ax-pr 5395  ax-un 7761
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-3an 1105  df-tru 1572  df-fal 1582  df-ex 1812  df-nf 1816  df-sb 2101  df-mo 2567  df-eu 2597  df-clab 2742  df-cleq 2755  df-clel 2839  df-nfc 2913  df-ne 2960  df-ral 3081  df-rex 3091  df-rmo 3369  df-reu 3370  df-rab 3417  df-v 3456  df-sbc 3743  df-csb 3852  df-ss 3901  df-pss 4017  df-dif 4050  df-in 4094  df-un 4154  df-nul 4282  df-if 4486  df-pw 4562  df-sn 4589  df-pr 4591  df-tp 4593  df-op 4839  df-ot 4862  df-uni 4871  df-int 4911  df-iun 4956  df-br 5107  df-opab 5171  df-mpt 5190  df-tr 5216  df-id 5550  df-eprel 5555  df-po 5563  df-so 5564  df-fr 5608  df-se 5609  df-we 5610  df-xp 5661  df-rel 5662  df-cnv 5663  df-co 5664  df-dm 5665  df-rn 5666  df-res 5667  df-ima 5668  df-pred 6311  df-ord 6372  df-on 6373  df-lim 6374  df-suc 6375  df-iota 6501  df-fun 6549  df-fn 6550  df-f 6551  df-f1 6552  df-fo 6553  df-f1o 6554  df-fv 6555  df-riota 7387  df-ov 7433  df-oprab 7434  df-mpo 7435  df-om 7888  df-1st 8011  df-2nd 8012  df-frecs 8313  df-wrecs 8344  df-recs 8393  df-rdg 8432  df-1o 8490  df-2o 8491  df-nadd 8689  df-no 28015  df-lts 28016  df-bday 28017  df-les 28117  df-slts 28159  df-cuts 28161  df-0s 28208  df-1s 28209  df-made 28228  df-old 28229  df-left 28231  df-right 28232  df-norec 28339  df-norec2 28350  df-adds 28361  df-negs 28422  df-subs 28423  df-muls 28508  df-n0s 28715  df-nns 28716  df-zs 28780
This theorem is used by:  zsoring  28810  zexpscl  28835  pw2cutp1  28862  z12addscl  28878
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