Theorem nla0002 42885

Description: Extending a linear order to subsets, the empty set is less than any subset. Note in [Alling], p. 3. (Contributed by RP, 28-Nov-2023.)

Hypotheses

Ref	Expression
nla0001.defsslt	⊢ < = {⟨𝑎, 𝑏⟩ ∣ (𝑎 ⊆ 𝑆 ∧ 𝑏 ⊆ 𝑆 ∧ ∀𝑥 ∈ 𝑎 ∀𝑦 ∈ 𝑏 𝑥𝑅𝑦)}
nla0001.set	⊢ (𝜑 → 𝐴 ∈ V)
nla0002.sset	⊢ (𝜑 → 𝐴 ⊆ 𝑆)

Assertion

Ref	Expression
nla0002	⊢ (𝜑 → ∅ < 𝐴)

Distinct variable groups:   𝐴,𝑎,𝑏,𝑥,𝑦   𝑅,𝑎,𝑏   𝑆,𝑎,𝑏

Allowed substitution hints:   𝜑(𝑥,𝑦,𝑎,𝑏)   𝑅(𝑥,𝑦)   𝑆(𝑥,𝑦)   < (𝑥,𝑦,𝑎,𝑏)

Proof of Theorem nla0002

Step	Hyp	Ref	Expression
1		0ex 5311	. . 3 ⊢ ∅ ∈ V
2	1	a1i 11	. 2 ⊢ (𝜑 → ∅ ∈ V)
3		nla0001.set	. 2 ⊢ (𝜑 → 𝐴 ∈ V)
4		0ss 4400	. . . 4 ⊢ ∅ ⊆ 𝑆
5	4	a1i 11	. . 3 ⊢ (𝜑 → ∅ ⊆ 𝑆)
6		nla0002.sset	. . 3 ⊢ (𝜑 → 𝐴 ⊆ 𝑆)
7		ral0 4516	. . . 4 ⊢ ∀𝑥 ∈ ∅ ∀𝑦 ∈ 𝐴 𝑥𝑅𝑦
8	7	a1i 11	. . 3 ⊢ (𝜑 → ∀𝑥 ∈ ∅ ∀𝑦 ∈ 𝐴 𝑥𝑅𝑦)
9	5, 6, 8	3jca 1125	. 2 ⊢ (𝜑 → (∅ ⊆ 𝑆 ∧ 𝐴 ⊆ 𝑆 ∧ ∀𝑥 ∈ ∅ ∀𝑦 ∈ 𝐴 𝑥𝑅𝑦))
10		nla0001.defsslt	. . 3 ⊢ < = {⟨𝑎, 𝑏⟩ ∣ (𝑎 ⊆ 𝑆 ∧ 𝑏 ⊆ 𝑆 ∧ ∀𝑥 ∈ 𝑎 ∀𝑦 ∈ 𝑏 𝑥𝑅𝑦)}
11	10	rp-brsslt 42884	. 2 ⊢ (∅ < 𝐴 ↔ ((∅ ∈ V ∧ 𝐴 ∈ V) ∧ (∅ ⊆ 𝑆 ∧ 𝐴 ⊆ 𝑆 ∧ ∀𝑥 ∈ ∅ ∀𝑦 ∈ 𝐴 𝑥𝑅𝑦)))
12	2, 3, 9, 11	syl21anbrc 1341	1 ⊢ (𝜑 → ∅ < 𝐴)

Syntax hints:   → wi 4   ∧ w3a 1084   = wceq 1533   ∈ wcel 2098  ∀wral 3058  Vcvv 3473   ⊆ wss 3949  ∅c0 4326   class class class wbr 5152  {copab 5214

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-ext 2699  ax-sep 5303  ax-nul 5310  ax-pr 5433

This theorem depends on definitions:  df-bi 206  df-an 395  df-or 846  df-3an 1086  df-tru 1536  df-fal 1546  df-ex 1774  df-sb 2060  df-clab 2706  df-cleq 2720  df-clel 2806  df-ral 3059  df-rex 3068  df-rab 3431  df-v 3475  df-dif 3952  df-un 3954  df-in 3956  df-ss 3966  df-nul 4327  df-if 4533  df-sn 4633  df-pr 4635  df-op 4639  df-br 5153  df-opab 5215  df-xp 5688

This theorem is referenced by:  nla0001  42887