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Theorem xpss12 4473
 Description: Subset theorem for cross product. Generalization of Theorem 101 of [Suppes] p. 52. (Contributed by NM, 26-Aug-1995.) (Proof shortened by Andrew Salmon, 27-Aug-2011.)
Assertion
Ref Expression
xpss12 ((𝐴𝐵𝐶𝐷) → (𝐴 × 𝐶) ⊆ (𝐵 × 𝐷))

Proof of Theorem xpss12
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 ssel 2967 . . . 4 (𝐴𝐵 → (𝑥𝐴𝑥𝐵))
2 ssel 2967 . . . 4 (𝐶𝐷 → (𝑦𝐶𝑦𝐷))
31, 2im2anan9 540 . . 3 ((𝐴𝐵𝐶𝐷) → ((𝑥𝐴𝑦𝐶) → (𝑥𝐵𝑦𝐷)))
43ssopab2dv 4043 . 2 ((𝐴𝐵𝐶𝐷) → {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)} ⊆ {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐵𝑦𝐷)})
5 df-xp 4379 . 2 (𝐴 × 𝐶) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐴𝑦𝐶)}
6 df-xp 4379 . 2 (𝐵 × 𝐷) = {⟨𝑥, 𝑦⟩ ∣ (𝑥𝐵𝑦𝐷)}
74, 5, 63sstr4g 3014 1 ((𝐴𝐵𝐶𝐷) → (𝐴 × 𝐶) ⊆ (𝐵 × 𝐷))
 Colors of variables: wff set class Syntax hints:   → wi 4   ∧ wa 101   ∈ wcel 1409   ⊆ wss 2945  {copab 3845   × cxp 4371 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 640  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-10 1412  ax-11 1413  ax-i12 1414  ax-bndl 1415  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038 This theorem depends on definitions:  df-bi 114  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-nfc 2183  df-in 2952  df-ss 2959  df-opab 3847  df-xp 4379 This theorem is referenced by:  xpss  4474  xpss1  4476  xpss2  4477  djussxp  4509  ssxpbm  4784  ssrnres  4791  cossxp  4871  relrelss  4872  fssxp  5086  oprabss  5618  dmaddpi  6481  dmmulpi  6482  rexpssxrxp  7129  ltrelxr  7139  dfz2  8371
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