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Theorem pltn2lp 17437

Description: The less-than relation has no 2-cycle loops. (pssn2lp 3968 analog.) (Contributed by NM, 2-Dec-2011.)

**Hypotheses**
Ref	Expression
pltnlt.b	⊢ 𝐵 = (Base‘𝐾)
pltnlt.s	⊢ < = (lt‘𝐾)

**Assertion**
Ref	Expression
pltn2lp	⊢ ((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ¬ (𝑋 < 𝑌 ∧ 𝑌 < 𝑋))

**Proof of Theorem pltn2lp**
Step	Hyp	Ref	Expression
1		pltnlt.b	. . . . 5 ⊢ 𝐵 = (Base‘𝐾)
2		eqid 2778	. . . . 5 ⊢ (le‘𝐾) = (le‘𝐾)
3		pltnlt.s	. . . . 5 ⊢ < = (lt‘𝐾)
4	1, 2, 3	pltnle 17434	. . . 4 ⊢ (((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) ∧ 𝑋 < 𝑌) → ¬ 𝑌(le‘𝐾)𝑋)
5	4	ex 405	. . 3 ⊢ ((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 < 𝑌 → ¬ 𝑌(le‘𝐾)𝑋))
6	2, 3	pltle 17429	. . . 4 ⊢ ((𝐾 ∈ Poset ∧ 𝑌 ∈ 𝐵 ∧ 𝑋 ∈ 𝐵) → (𝑌 < 𝑋 → 𝑌(le‘𝐾)𝑋))
7	6	3com23 1106	. . 3 ⊢ ((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑌 < 𝑋 → 𝑌(le‘𝐾)𝑋))
8	5, 7	nsyld 156	. 2 ⊢ ((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 < 𝑌 → ¬ 𝑌 < 𝑋))
9		imnan 391	. 2 ⊢ ((𝑋 < 𝑌 → ¬ 𝑌 < 𝑋) ↔ ¬ (𝑋 < 𝑌 ∧ 𝑌 < 𝑋))
10	8, 9	sylib 210	1 ⊢ ((𝐾 ∈ Poset ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ¬ (𝑋 < 𝑌 ∧ 𝑌 < 𝑋))

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 → wi 4 ∧ wa 387 ∧ w3a 1068 = wceq 1507 ∈ wcel 2050 class class class wbr 4929 ‘cfv 6188 Basecbs 16339 lecple 16428 Posetcpo 17408 ltcplt 17409

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1758 ax-4 1772 ax-5 1869 ax-6 1928 ax-7 1965 ax-8 2052 ax-9 2059 ax-10 2079 ax-11 2093 ax-12 2106 ax-13 2301 ax-ext 2750 ax-sep 5060 ax-nul 5067 ax-pr 5186

This theorem depends on definitions: df-bi 199 df-an 388 df-or 834 df-3an 1070 df-tru 1510 df-ex 1743 df-nf 1747 df-sb 2016 df-mo 2547 df-eu 2584 df-clab 2759 df-cleq 2771 df-clel 2846 df-nfc 2918 df-ne 2968 df-ral 3093 df-rex 3094 df-rab 3097 df-v 3417 df-sbc 3682 df-dif 3832 df-un 3834 df-in 3836 df-ss 3843 df-nul 4179 df-if 4351 df-sn 4442 df-pr 4444 df-op 4448 df-uni 4713 df-br 4930 df-opab 4992 df-mpt 5009 df-id 5312 df-xp 5413 df-rel 5414 df-cnv 5415 df-co 5416 df-dm 5417 df-iota 6152 df-fun 6190 df-fv 6196 df-proset 17396 df-poset 17414 df-plt 17426

This theorem is referenced by: plttr 17438

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