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Theorem zmulscld 28783
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 28770 . . 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 28770 . . 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 3235 . . . . 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 3139 . . . 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 3235 . . . 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 28710 . . . . . . . . . . 11 (𝑥 ∈ ℕs → 𝑥 ∈ No)
1211ad2antrr 739 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑥 ∈ No)
13 nnno 28710 . . . . . . . . . . 11 (𝑦 ∈ ℕs → 𝑦 ∈ No)
1413ad2antrl 741 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑦 ∈ No)
1512, 14subscld 28449 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 −s 𝑦) ∈ No)
16 nnno 28710 . . . . . . . . . 10 (𝑧 ∈ ℕs → 𝑧 ∈ No)
1716ad2antlr 740 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑧 ∈ No)
18 nnno 28710 . . . . . . . . . 10 (𝑤 ∈ ℕs → 𝑤 ∈ No)
1918ad2antll 742 . . . . . . . . 9 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → 𝑤 ∈ No)
2015, 17, 19subsdid 28544 . . . . . . . 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 28733 . . . . . . . . . . . . 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 28712 . . . . . . . . . . 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 28733 . . . . . . . . . . . . 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 28712 . . . . . . . . . . 11 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑧) ∈ No)
2923, 28subscld 28449 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 ·s 𝑧) −s (𝑦 ·s 𝑧)) ∈ No)
30 nnmulscl 28733 . . . . . . . . . . . 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 28712 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑥 ·s 𝑤) ∈ No)
33 nnmulscl 28733 . . . . . . . . . . . 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 28712 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → (𝑦 ·s 𝑤) ∈ No)
3629, 32, 35subsubs2d 28481 . . . . . . . . 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 28545 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s 𝑧) = ((𝑥 ·s 𝑧) −s (𝑦 ·s 𝑧)))
3812, 14, 19subsdird 28545 . . . . . . . . . 10 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s 𝑤) = ((𝑥 ·s 𝑤) −s (𝑦 ·s 𝑤)))
3937, 38oveq12d 7438 . . . . . . . . 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 28487 . . . . . . . . 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 2806 . . . . . . . 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 2796 . . . . . . 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 28732 . . . . . . . . . 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 28732 . . . . . . . . . 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 2761 . . . . . . . . . 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 7469 . . . . . . . . . 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 28770 . . . . . . . 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 2861 . . . . . 6 (((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) ∧ (𝑦 ∈ ℕs ∧ 𝑤 ∈ ℕs)) → ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)) ∈ ℤs)
54 oveq12 7429 . . . . . . 7 ((𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) = ((𝑥 −s 𝑦) ·s (𝑧 −s 𝑤)))
5554eleq1d 2846 . . . . . 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 3220 . . . 4 ((𝑥 ∈ ℕs ∧ 𝑧 ∈ ℕs) → (∃𝑦 ∈ ℕs ∃𝑤 ∈ ℕs (𝐴 = (𝑥 −s 𝑦) ∧ 𝐵 = (𝑧 −s 𝑤)) → (𝐴 ·s 𝐵) ∈ ℤs))
5857rexlimivv 3205 . . 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 1570   ∈ wcel 2145  ∃wrex 3087  (class class class)co 7420  Nocsur 27997   +s cadds 28345   −s csubs 28406   ·s cmuls 28492  ℕscnns 28699  ℤsczs 28764
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-10 2178  ax-11 2194  ax-12 2213  ax-ext 2733  ax-rep 5232  ax-sep 5249  ax-nul 5260  ax-pow 5327  ax-pr 5391  ax-un 7751
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1813  df-nf 1817  df-sb 2100  df-mo 2565  df-eu 2595  df-clab 2740  df-cleq 2753  df-clel 2836  df-nfc 2910  df-ne 2957  df-ral 3078  df-rex 3088  df-rmo 3366  df-reu 3367  df-rab 3414  df-v 3453  df-sbc 3740  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-pss 3919  df-nul 4280  df-if 4483  df-pw 4559  df-sn 4585  df-pr 4587  df-tp 4589  df-op 4591  df-ot 4593  df-uni 4868  df-int 4908  df-iun 4953  df-br 5104  df-opab 5168  df-mpt 5187  df-tr 5213  df-id 5546  df-eprel 5551  df-po 5559  df-so 5560  df-fr 5604  df-se 5605  df-we 5606  df-xp 5657  df-rel 5658  df-cnv 5659  df-co 5660  df-dm 5661  df-rn 5662  df-res 5663  df-ima 5664  df-pred 6304  df-ord 6365  df-on 6366  df-lim 6367  df-suc 6368  df-iota 6494  df-fun 6540  df-fn 6541  df-f 6542  df-f1 6543  df-fo 6544  df-f1o 6545  df-fv 6546  df-riota 7377  df-ov 7423  df-oprab 7424  df-mpo 7425  df-om 7878  df-1st 8001  df-2nd 8002  df-frecs 8299  df-wrecs 8330  df-recs 8379  df-rdg 8418  df-1o 8476  df-2o 8477  df-nadd 8675  df-no 28000  df-lts 28001  df-bday 28002  df-les 28102  df-slts 28144  df-cuts 28146  df-0s 28193  df-1s 28194  df-made 28213  df-old 28214  df-left 28216  df-right 28217  df-norec 28324  df-norec2 28335  df-adds 28346  df-negs 28407  df-subs 28408  df-muls 28493  df-n0s 28700  df-nns 28701  df-zs 28765
This theorem is used by:  zsoring  28795  zexpscl  28820  pw2cutp1  28847  z12addscl  28863
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