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Description: Write a poset structure in terms of the proper-class poset predicate (strict less than version). (Contributed by Mario Carneiro, 8-Feb-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | pospo.b | ⊢ 𝐵 = ( Base ‘ 𝐾 ) | |
| pospo.l | ⊢ ≤ = ( le ‘ 𝐾 ) | ||
| pospo.s | ⊢ < = ( lt ‘ 𝐾 ) | ||
| Assertion | pospo | ⊢ ( 𝐾 ∈ 𝑉 → ( 𝐾 ∈ Poset ↔ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pospo.b | ⊢ 𝐵 = ( Base ‘ 𝐾 ) | |
| 2 | pospo.l | ⊢ ≤ = ( le ‘ 𝐾 ) | |
| 3 | pospo.s | ⊢ < = ( lt ‘ 𝐾 ) | |
| 4 | 3 | pltirr | ⊢ ( ( 𝐾 ∈ Poset ∧ 𝑥 ∈ 𝐵 ) → ¬ 𝑥 < 𝑥 ) |
| 5 | 1 3 | plttr | ⊢ ( ( 𝐾 ∈ Poset ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 < 𝑧 ) ) |
| 6 | 4 5 | ispod | ⊢ ( 𝐾 ∈ Poset → < Po 𝐵 ) |
| 7 | relres | ⊢ Rel ( I ↾ 𝐵 ) | |
| 8 | 7 | a1i | ⊢ ( 𝐾 ∈ Poset → Rel ( I ↾ 𝐵 ) ) |
| 9 | opabresid | ⊢ ( I ↾ 𝐵 ) = { 〈 𝑥 , 𝑦 〉 ∣ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) } | |
| 10 | 9 | eqcomi | ⊢ { 〈 𝑥 , 𝑦 〉 ∣ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) } = ( I ↾ 𝐵 ) |
| 11 | 10 | eleq2i | ⊢ ( 〈 𝑥 , 𝑦 〉 ∈ { 〈 𝑥 , 𝑦 〉 ∣ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) } ↔ 〈 𝑥 , 𝑦 〉 ∈ ( I ↾ 𝐵 ) ) |
| 12 | opabidw | ⊢ ( 〈 𝑥 , 𝑦 〉 ∈ { 〈 𝑥 , 𝑦 〉 ∣ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) } ↔ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) ) | |
| 13 | 11 12 | bitr3i | ⊢ ( 〈 𝑥 , 𝑦 〉 ∈ ( I ↾ 𝐵 ) ↔ ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) ) |
| 14 | 1 2 | posref | ⊢ ( ( 𝐾 ∈ Poset ∧ 𝑥 ∈ 𝐵 ) → 𝑥 ≤ 𝑥 ) |
| 15 | df-br | ⊢ ( 𝑥 ≤ 𝑦 ↔ 〈 𝑥 , 𝑦 〉 ∈ ≤ ) | |
| 16 | breq2 | ⊢ ( 𝑦 = 𝑥 → ( 𝑥 ≤ 𝑦 ↔ 𝑥 ≤ 𝑥 ) ) | |
| 17 | 15 16 | bitr3id | ⊢ ( 𝑦 = 𝑥 → ( 〈 𝑥 , 𝑦 〉 ∈ ≤ ↔ 𝑥 ≤ 𝑥 ) ) |
| 18 | 14 17 | syl5ibrcom | ⊢ ( ( 𝐾 ∈ Poset ∧ 𝑥 ∈ 𝐵 ) → ( 𝑦 = 𝑥 → 〈 𝑥 , 𝑦 〉 ∈ ≤ ) ) |
| 19 | 18 | expimpd | ⊢ ( 𝐾 ∈ Poset → ( ( 𝑥 ∈ 𝐵 ∧ 𝑦 = 𝑥 ) → 〈 𝑥 , 𝑦 〉 ∈ ≤ ) ) |
| 20 | 13 19 | biimtrid | ⊢ ( 𝐾 ∈ Poset → ( 〈 𝑥 , 𝑦 〉 ∈ ( I ↾ 𝐵 ) → 〈 𝑥 , 𝑦 〉 ∈ ≤ ) ) |
| 21 | 8 20 | relssdv | ⊢ ( 𝐾 ∈ Poset → ( I ↾ 𝐵 ) ⊆ ≤ ) |
| 22 | 6 21 | jca | ⊢ ( 𝐾 ∈ Poset → ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) |
| 23 | simpl | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) → 𝐾 ∈ 𝑉 ) | |
| 24 | 1 | a1i | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) → 𝐵 = ( Base ‘ 𝐾 ) ) |
| 25 | 2 | a1i | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) → ≤ = ( le ‘ 𝐾 ) ) |
| 26 | equid | ⊢ 𝑥 = 𝑥 | |
| 27 | simpr | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → 𝑥 ∈ 𝐵 ) | |
| 28 | resieq | ⊢ ( ( 𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐵 ) → ( 𝑥 ( I ↾ 𝐵 ) 𝑥 ↔ 𝑥 = 𝑥 ) ) | |
| 29 | 27 27 28 | syl2anc | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → ( 𝑥 ( I ↾ 𝐵 ) 𝑥 ↔ 𝑥 = 𝑥 ) ) |
| 30 | 26 29 | mpbiri | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → 𝑥 ( I ↾ 𝐵 ) 𝑥 ) |
| 31 | simplrr | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → ( I ↾ 𝐵 ) ⊆ ≤ ) | |
| 32 | 31 | ssbrd | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → ( 𝑥 ( I ↾ 𝐵 ) 𝑥 → 𝑥 ≤ 𝑥 ) ) |
| 33 | 30 32 | mpd | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ) → 𝑥 ≤ 𝑥 ) |
| 34 | 1 2 3 | pleval2i | ⊢ ( ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( 𝑥 ≤ 𝑦 → ( 𝑥 < 𝑦 ∨ 𝑥 = 𝑦 ) ) ) |
| 35 | 34 | 3adant1 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( 𝑥 ≤ 𝑦 → ( 𝑥 < 𝑦 ∨ 𝑥 = 𝑦 ) ) ) |
| 36 | 1 2 3 | pleval2i | ⊢ ( ( 𝑦 ∈ 𝐵 ∧ 𝑥 ∈ 𝐵 ) → ( 𝑦 ≤ 𝑥 → ( 𝑦 < 𝑥 ∨ 𝑦 = 𝑥 ) ) ) |
| 37 | 36 | ancoms | ⊢ ( ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( 𝑦 ≤ 𝑥 → ( 𝑦 < 𝑥 ∨ 𝑦 = 𝑥 ) ) ) |
| 38 | 37 | 3adant1 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( 𝑦 ≤ 𝑥 → ( 𝑦 < 𝑥 ∨ 𝑦 = 𝑥 ) ) ) |
| 39 | simprl | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) → < Po 𝐵 ) | |
| 40 | po2nr | ⊢ ( ( < Po 𝐵 ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) ) → ¬ ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑥 ) ) | |
| 41 | 40 | 3impb | ⊢ ( ( < Po 𝐵 ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ¬ ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑥 ) ) |
| 42 | 39 41 | syl3an1 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ¬ ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑥 ) ) |
| 43 | 42 | pm2.21d | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑥 ) → 𝑥 = 𝑦 ) ) |
| 44 | simpl | ⊢ ( ( 𝑥 = 𝑦 ∧ 𝑦 < 𝑥 ) → 𝑥 = 𝑦 ) | |
| 45 | 44 | a1i | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( 𝑥 = 𝑦 ∧ 𝑦 < 𝑥 ) → 𝑥 = 𝑦 ) ) |
| 46 | simpr | ⊢ ( ( 𝑥 < 𝑦 ∧ 𝑦 = 𝑥 ) → 𝑦 = 𝑥 ) | |
| 47 | 46 | equcomd | ⊢ ( ( 𝑥 < 𝑦 ∧ 𝑦 = 𝑥 ) → 𝑥 = 𝑦 ) |
| 48 | 47 | a1i | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 = 𝑥 ) → 𝑥 = 𝑦 ) ) |
| 49 | simpl | ⊢ ( ( 𝑥 = 𝑦 ∧ 𝑦 = 𝑥 ) → 𝑥 = 𝑦 ) | |
| 50 | 49 | a1i | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( 𝑥 = 𝑦 ∧ 𝑦 = 𝑥 ) → 𝑥 = 𝑦 ) ) |
| 51 | 43 45 48 50 | ccased | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( ( 𝑥 < 𝑦 ∨ 𝑥 = 𝑦 ) ∧ ( 𝑦 < 𝑥 ∨ 𝑦 = 𝑥 ) ) → 𝑥 = 𝑦 ) ) |
| 52 | 35 38 51 | syl2and | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ) → ( ( 𝑥 ≤ 𝑦 ∧ 𝑦 ≤ 𝑥 ) → 𝑥 = 𝑦 ) ) |
| 53 | simpr1 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → 𝑥 ∈ 𝐵 ) | |
| 54 | simpr2 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → 𝑦 ∈ 𝐵 ) | |
| 55 | 53 54 34 | syl2anc | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( 𝑥 ≤ 𝑦 → ( 𝑥 < 𝑦 ∨ 𝑥 = 𝑦 ) ) ) |
| 56 | simpr3 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → 𝑧 ∈ 𝐵 ) | |
| 57 | 1 2 3 | pleval2i | ⊢ ( ( 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) → ( 𝑦 ≤ 𝑧 → ( 𝑦 < 𝑧 ∨ 𝑦 = 𝑧 ) ) ) |
| 58 | 54 56 57 | syl2anc | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( 𝑦 ≤ 𝑧 → ( 𝑦 < 𝑧 ∨ 𝑦 = 𝑧 ) ) ) |
| 59 | potr | ⊢ ( ( < Po 𝐵 ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 < 𝑧 ) ) | |
| 60 | 39 59 | sylan | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 < 𝑧 ) ) |
| 61 | simpll | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → 𝐾 ∈ 𝑉 ) | |
| 62 | 2 3 | pltle | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ 𝑥 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) → ( 𝑥 < 𝑧 → 𝑥 ≤ 𝑧 ) ) |
| 63 | 61 53 56 62 | syl3anc | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( 𝑥 < 𝑧 → 𝑥 ≤ 𝑧 ) ) |
| 64 | 60 63 | syld | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 ≤ 𝑧 ) ) |
| 65 | breq1 | ⊢ ( 𝑥 = 𝑦 → ( 𝑥 < 𝑧 ↔ 𝑦 < 𝑧 ) ) | |
| 66 | 65 | biimpar | ⊢ ( ( 𝑥 = 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 < 𝑧 ) |
| 67 | 66 63 | syl5 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 = 𝑦 ∧ 𝑦 < 𝑧 ) → 𝑥 ≤ 𝑧 ) ) |
| 68 | breq2 | ⊢ ( 𝑦 = 𝑧 → ( 𝑥 < 𝑦 ↔ 𝑥 < 𝑧 ) ) | |
| 69 | 68 | biimpac | ⊢ ( ( 𝑥 < 𝑦 ∧ 𝑦 = 𝑧 ) → 𝑥 < 𝑧 ) |
| 70 | 69 63 | syl5 | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 < 𝑦 ∧ 𝑦 = 𝑧 ) → 𝑥 ≤ 𝑧 ) ) |
| 71 | 53 33 | syldan | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → 𝑥 ≤ 𝑥 ) |
| 72 | eqtr | ⊢ ( ( 𝑥 = 𝑦 ∧ 𝑦 = 𝑧 ) → 𝑥 = 𝑧 ) | |
| 73 | 72 | breq2d | ⊢ ( ( 𝑥 = 𝑦 ∧ 𝑦 = 𝑧 ) → ( 𝑥 ≤ 𝑥 ↔ 𝑥 ≤ 𝑧 ) ) |
| 74 | 71 73 | syl5ibcom | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 = 𝑦 ∧ 𝑦 = 𝑧 ) → 𝑥 ≤ 𝑧 ) ) |
| 75 | 64 67 70 74 | ccased | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( ( 𝑥 < 𝑦 ∨ 𝑥 = 𝑦 ) ∧ ( 𝑦 < 𝑧 ∨ 𝑦 = 𝑧 ) ) → 𝑥 ≤ 𝑧 ) ) |
| 76 | 55 58 75 | syl2and | ⊢ ( ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ∧ ( 𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵 ) ) → ( ( 𝑥 ≤ 𝑦 ∧ 𝑦 ≤ 𝑧 ) → 𝑥 ≤ 𝑧 ) ) |
| 77 | 23 24 25 33 52 76 | isposd | ⊢ ( ( 𝐾 ∈ 𝑉 ∧ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) → 𝐾 ∈ Poset ) |
| 78 | 77 | ex | ⊢ ( 𝐾 ∈ 𝑉 → ( ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) → 𝐾 ∈ Poset ) ) |
| 79 | 22 78 | impbid2 | ⊢ ( 𝐾 ∈ 𝑉 → ( 𝐾 ∈ Poset ↔ ( < Po 𝐵 ∧ ( I ↾ 𝐵 ) ⊆ ≤ ) ) ) |