Metamath Proof Explorer


Theorem cvlcvr1

Description: The covering property. Proposition 1(ii) in Kalmbach p. 140 (and its converse). ( chcv1 analog.) (Contributed by NM, 5-Nov-2012)

Ref Expression
Hypotheses cvlcvr1.b ⊢ B = Base K
cvlcvr1.l ⊢ ≤ ˙ = ≤ K
cvlcvr1.j ⊢ ∨ ˙ = join ⁡ K
cvlcvr1.c ⊢ C = ⋖ K
cvlcvr1.a ⊢ A = Atoms ⁡ K
Assertion cvlcvr1 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X ↔ X C X ∨ ˙ P

Proof

Step Hyp Ref Expression
1 cvlcvr1.b ⊢ B = Base K
2 cvlcvr1.l ⊢ ≤ ˙ = ≤ K
3 cvlcvr1.j ⊢ ∨ ˙ = join ⁡ K
4 cvlcvr1.c ⊢ C = ⋖ K
5 cvlcvr1.a ⊢ A = Atoms ⁡ K
6 simp13 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → K ∈ CvLat
7 cvllat ⊢ K ∈ CvLat → K ∈ Lat
8 6 7 syl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → K ∈ Lat
9 simp2 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → X ∈ B
10 1 5 atbase ⊢ P ∈ A → P ∈ B
11 10 3ad2ant3 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → P ∈ B
12 eqid ⊢ < K = < K
13 1 2 12 3 latnle ⊢ K ∈ Lat ∧ X ∈ B ∧ P ∈ B → ¬ P ≤ ˙ X ↔ X < K X ∨ ˙ P
14 8 9 11 13 syl3anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X ↔ X < K X ∨ ˙ P
15 14 biimpd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X → X < K X ∨ ˙ P
16 simpl13 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → K ∈ CvLat
17 16 7 syl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → K ∈ Lat
18 simprll ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → z ∈ B
19 simpl2 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X ∈ B
20 simpl3 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → P ∈ A
21 20 10 syl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → P ∈ B
22 1 3 latjcl ⊢ K ∈ Lat ∧ X ∈ B ∧ P ∈ B → X ∨ ˙ P ∈ B
23 17 19 21 22 syl3anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X ∨ ˙ P ∈ B
24 simprrr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → z ≤ ˙ X ∨ ˙ P
25 simprrl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X < K z
26 simpl11 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → K ∈ OML
27 simpl12 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → K ∈ CLat
28 cvlatl ⊢ K ∈ CvLat → K ∈ AtLat
29 16 28 syl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → K ∈ AtLat
30 1 2 12 5 atlrelat1 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ AtLat ∧ X ∈ B ∧ z ∈ B → X < K z → ∃ q ∈ A ¬ q ≤ ˙ X ∧ q ≤ ˙ z
31 26 27 29 19 18 30 syl311anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X < K z → ∃ q ∈ A ¬ q ≤ ˙ X ∧ q ≤ ˙ z
32 25 31 mpd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → ∃ q ∈ A ¬ q ≤ ˙ X ∧ q ≤ ˙ z
33 17 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → K ∈ Lat
34 1 5 atbase ⊢ q ∈ A → q ∈ B
35 34 ad2antrl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → q ∈ B
36 18 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → z ∈ B
37 23 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ∨ ˙ P ∈ B
38 simprrr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → q ≤ ˙ z
39 24 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → z ≤ ˙ X ∨ ˙ P
40 1 2 33 35 36 37 38 39 lattrd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → q ≤ ˙ X ∨ ˙ P
41 16 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → K ∈ CvLat
42 simprl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → q ∈ A
43 simpll3 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → P ∈ A
44 simpll2 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ∈ B
45 simprrl ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → ¬ q ≤ ˙ X
46 1 2 3 5 cvlexch1 ⊢ K ∈ CvLat ∧ q ∈ A ∧ P ∈ A ∧ X ∈ B ∧ ¬ q ≤ ˙ X → q ≤ ˙ X ∨ ˙ P → P ≤ ˙ X ∨ ˙ q
47 41 42 43 44 45 46 syl131anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → q ≤ ˙ X ∨ ˙ P → P ≤ ˙ X ∨ ˙ q
48 40 47 mpd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → P ≤ ˙ X ∨ ˙ q
49 simprlr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → ¬ P ≤ ˙ X
50 49 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → ¬ P ≤ ˙ X
51 1 2 3 5 cvlexchb1 ⊢ K ∈ CvLat ∧ P ∈ A ∧ q ∈ A ∧ X ∈ B ∧ ¬ P ≤ ˙ X → P ≤ ˙ X ∨ ˙ q ↔ X ∨ ˙ P = X ∨ ˙ q
52 41 43 42 44 50 51 syl131anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → P ≤ ˙ X ∨ ˙ q ↔ X ∨ ˙ P = X ∨ ˙ q
53 48 52 mpbid ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ∨ ˙ P = X ∨ ˙ q
54 2 12 pltle ⊢ K ∈ OML ∧ X ∈ B ∧ z ∈ B → X < K z → X ≤ ˙ z
55 26 19 18 54 syl3anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X < K z → X ≤ ˙ z
56 25 55 mpd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X ≤ ˙ z
57 56 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ≤ ˙ z
58 1 2 3 latjle12 ⊢ K ∈ Lat ∧ X ∈ B ∧ q ∈ B ∧ z ∈ B → X ≤ ˙ z ∧ q ≤ ˙ z ↔ X ∨ ˙ q ≤ ˙ z
59 33 44 35 36 58 syl13anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ≤ ˙ z ∧ q ≤ ˙ z ↔ X ∨ ˙ q ≤ ˙ z
60 57 38 59 mpbi2and ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ∨ ˙ q ≤ ˙ z
61 53 60 eqbrtrd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P ∧ q ∈ A ∧ ¬ q ≤ ˙ X ∧ q ≤ ˙ z → X ∨ ˙ P ≤ ˙ z
62 32 61 rexlimddv ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → X ∨ ˙ P ≤ ˙ z
63 1 2 17 18 23 24 62 latasymd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B ∧ ¬ P ≤ ˙ X ∧ X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
64 63 exp44 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → z ∈ B → ¬ P ≤ ˙ X → X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
65 64 imp ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ z ∈ B → ¬ P ≤ ˙ X → X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
66 65 ralrimdva ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X → ∀ z ∈ B X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
67 15 66 jcad ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X → X < K X ∨ ˙ P ∧ ∀ z ∈ B X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
68 8 9 11 22 syl3anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → X ∨ ˙ P ∈ B
69 1 2 12 4 cvrval2 ⊢ K ∈ Lat ∧ X ∈ B ∧ X ∨ ˙ P ∈ B → X C X ∨ ˙ P ↔ X < K X ∨ ˙ P ∧ ∀ z ∈ B X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
70 8 9 68 69 syl3anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → X C X ∨ ˙ P ↔ X < K X ∨ ˙ P ∧ ∀ z ∈ B X < K z ∧ z ≤ ˙ X ∨ ˙ P → z = X ∨ ˙ P
71 67 70 sylibrd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X → X C X ∨ ˙ P
72 8 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ X C X ∨ ˙ P → K ∈ Lat
73 simpl2 ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ X C X ∨ ˙ P → X ∈ B
74 68 adantr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ X C X ∨ ˙ P → X ∨ ˙ P ∈ B
75 simpr ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ X C X ∨ ˙ P → X C X ∨ ˙ P
76 1 12 4 cvrlt ⊢ K ∈ Lat ∧ X ∈ B ∧ X ∨ ˙ P ∈ B ∧ X C X ∨ ˙ P → X < K X ∨ ˙ P
77 72 73 74 75 76 syl31anc ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A ∧ X C X ∨ ˙ P → X < K X ∨ ˙ P
78 77 ex ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → X C X ∨ ˙ P → X < K X ∨ ˙ P
79 78 14 sylibrd ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → X C X ∨ ˙ P → ¬ P ≤ ˙ X
80 71 79 impbid ⊢ K ∈ OML ∧ K ∈ CLat ∧ K ∈ CvLat ∧ X ∈ B ∧ P ∈ A → ¬ P ≤ ˙ X ↔ X C X ∨ ˙ P