Theorem ordtriexmid 4498

Description: Ordinal trichotomy implies the law of the excluded middle (that is, decidability of an arbitrary proposition).

This theorem is stated in "Constructive ordinals", [Crosilla], p. "Set-theoretic principles incompatible with intuitionistic logic".

Also see exmidontri 7195 which is much the same theorem but biconditionalized and using the EXMID notation. (Contributed by Mario Carneiro and Jim Kingdon, 14-Nov-2018.)

Hypothesis

Ref	Expression
ordtriexmid.1	|- A. x e. On A. y e. On ( x e. y \/ x = y \/ y e. x )

Assertion

Ref	Expression
ordtriexmid	|- ( ph \/ -. ph )

Distinct variable groups:   x, y   ph, x

Allowed substitution hint:   ph( y)

Proof of Theorem ordtriexmid

Dummy variable z is distinct from all other variables.

Step	Hyp	Ref	Expression
1		noel 3413	. . . 4 |- -. { z e. { (/) } | ph } e. (/)
2		ordtriexmidlem 4496	. . . . . 6 |- { z e. { (/) } | ph } e. On
3		eleq1 2229	. . . . . . . 8 |- ( x = { z e. { (/) } | ph } -> ( x e. (/) <-> { z e. { (/) } | ph } e. (/) ) )
4		eqeq1 2172	. . . . . . . 8 |- ( x = { z e. { (/) } | ph } -> ( x = (/) <-> { z e. { (/) } | ph } = (/) ) )
5		eleq2 2230	. . . . . . . 8 |- ( x = { z e. { (/) } | ph } -> ( (/) e. x <-> (/) e. { z e. { (/) } | ph } ) )
6	3, 4, 5	3orbi123d 1301	. . . . . . 7 |- ( x = { z e. { (/) } | ph } -> ( ( x e. (/) \/ x = (/) \/ (/) e. x ) <-> ( { z e. { (/) } | ph } e. (/) \/ { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) ) )
7		0elon 4370	. . . . . . . 8 |- (/) e. On
8		0ex 4109	. . . . . . . . 9 |- (/) e. _V
9		eleq1 2229	. . . . . . . . . . 11 |- ( y = (/) -> ( y e. On <-> (/) e. On ) )
10	9	anbi2d 460	. . . . . . . . . 10 |- ( y = (/) -> ( ( x e. On /\ y e. On ) <-> ( x e. On /\ (/) e. On ) ) )
11		eleq2 2230	. . . . . . . . . . 11 |- ( y = (/) -> ( x e. y <-> x e. (/) ) )
12		eqeq2 2175	. . . . . . . . . . 11 |- ( y = (/) -> ( x = y <-> x = (/) ) )
13		eleq1 2229	. . . . . . . . . . 11 |- ( y = (/) -> ( y e. x <-> (/) e. x ) )
14	11, 12, 13	3orbi123d 1301	. . . . . . . . . 10 |- ( y = (/) -> ( ( x e. y \/ x = y \/ y e. x ) <-> ( x e. (/) \/ x = (/) \/ (/) e. x ) ) )
15	10, 14	imbi12d 233	. . . . . . . . 9 |- ( y = (/) -> ( ( ( x e. On /\ y e. On ) -> ( x e. y \/ x = y \/ y e. x ) ) <-> ( ( x e. On /\ (/) e. On ) -> ( x e. (/) \/ x = (/) \/ (/) e. x ) ) ) )
16		ordtriexmid.1	. . . . . . . . . 10 |- A. x e. On A. y e. On ( x e. y \/ x = y \/ y e. x )
17	16	rspec2 2555	. . . . . . . . 9 |- ( ( x e. On /\ y e. On ) -> ( x e. y \/ x = y \/ y e. x ) )
18	8, 15, 17	vtocl 2780	. . . . . . . 8 |- ( ( x e. On /\ (/) e. On ) -> ( x e. (/) \/ x = (/) \/ (/) e. x ) )
19	7, 18	mpan2 422	. . . . . . 7 |- ( x e. On -> ( x e. (/) \/ x = (/) \/ (/) e. x ) )
20	6, 19	vtoclga 2792	. . . . . 6 |- ( { z e. { (/) } | ph } e. On -> ( { z e. { (/) } | ph } e. (/) \/ { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) )
21	2, 20	ax-mp 5	. . . . 5 |- ( { z e. { (/) } | ph } e. (/) \/ { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } )
22		3orass 971	. . . . 5 |- ( ( { z e. { (/) } | ph } e. (/) \/ { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) <-> ( { z e. { (/) } | ph } e. (/) \/ ( { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) ) )
23	21, 22	mpbi 144	. . . 4 |- ( { z e. { (/) } | ph } e. (/) \/ ( { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) )
24	1, 23	mtpor 1415	. . 3 |- ( { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } )
25		ordtriexmidlem2 4497	. . . 4 |- ( { z e. { (/) } | ph } = (/) -> -. ph )
26	8	snid 3607	. . . . . 6 |- (/) e. { (/) }
27		biidd 171	. . . . . . 7 |- ( z = (/) -> ( ph <-> ph ) )
28	27	elrab3 2883	. . . . . 6 |- ( (/) e. { (/) } -> ( (/) e. { z e. { (/) } | ph } <-> ph ) )
29	26, 28	ax-mp 5	. . . . 5 |- ( (/) e. { z e. { (/) } | ph } <-> ph )
30	29	biimpi 119	. . . 4 |- ( (/) e. { z e. { (/) } | ph } -> ph )
31	25, 30	orim12i 749	. . 3 |- ( ( { z e. { (/) } | ph } = (/) \/ (/) e. { z e. { (/) } | ph } ) -> ( -. ph \/ ph ) )
32	24, 31	ax-mp 5	. 2 |- ( -. ph \/ ph )
33		orcom 718	. 2 |- ( ( ph \/ -. ph ) <-> ( -. ph \/ ph ) )
34	32, 33	mpbir 145	1 |- ( ph \/ -. ph )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 103   <-> wb 104   \/ wo 698   \/ w3o 967   = wceq 1343   e. wcel 2136   A.wral 2444   {crab 2448   (/)c0 3409   {csn 3576   Oncon0 4341

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-14 2139  ax-ext 2147  ax-sep 4100  ax-nul 4108  ax-pow 4153

This theorem depends on definitions:  df-bi 116  df-3or 969  df-3an 970  df-tru 1346  df-nf 1449  df-sb 1751  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-ral 2449  df-rex 2450  df-rab 2453  df-v 2728  df-dif 3118  df-un 3120  df-in 3122  df-ss 3129  df-nul 3410  df-pw 3561  df-sn 3582  df-uni 3790  df-tr 4081  df-iord 4344  df-on 4346  df-suc 4349

This theorem is referenced by: (None)