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Description: A nonempty, bounded-above set of reals has a supremum. Axiom 22 of 22 for real and complex numbers, justified by Theorem axpre-sup . Note: Normally new proofs would use axsup . (New usage is discouraged.) (Contributed by NM, 13-Oct-2005)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ax-pre-sup | ⊢ ( ( 𝐴 ⊆ ℝ ∧ 𝐴 ≠ ∅ ∧ ∃ 𝑥 ∈ ℝ ∀ 𝑦 ∈ 𝐴 𝑦 <ℝ 𝑥 ) → ∃ 𝑥 ∈ ℝ ( ∀ 𝑦 ∈ 𝐴 ¬ 𝑥 <ℝ 𝑦 ∧ ∀ 𝑦 ∈ ℝ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cA | ⊢ 𝐴 | |
| 1 | cr | ⊢ ℝ | |
| 2 | 0 1 | wss | ⊢ 𝐴 ⊆ ℝ |
| 3 | c0 | ⊢ ∅ | |
| 4 | 0 3 | wne | ⊢ 𝐴 ≠ ∅ |
| 5 | vx | ⊢ 𝑥 | |
| 6 | vy | ⊢ 𝑦 | |
| 7 | 6 | cv | ⊢ 𝑦 |
| 8 | cltrr | ⊢ <ℝ | |
| 9 | 5 | cv | ⊢ 𝑥 |
| 10 | 7 9 8 | wbr | ⊢ 𝑦 <ℝ 𝑥 |
| 11 | 10 6 0 | wral | ⊢ ∀ 𝑦 ∈ 𝐴 𝑦 <ℝ 𝑥 |
| 12 | 11 5 1 | wrex | ⊢ ∃ 𝑥 ∈ ℝ ∀ 𝑦 ∈ 𝐴 𝑦 <ℝ 𝑥 |
| 13 | 2 4 12 | w3a | ⊢ ( 𝐴 ⊆ ℝ ∧ 𝐴 ≠ ∅ ∧ ∃ 𝑥 ∈ ℝ ∀ 𝑦 ∈ 𝐴 𝑦 <ℝ 𝑥 ) |
| 14 | 9 7 8 | wbr | ⊢ 𝑥 <ℝ 𝑦 |
| 15 | 14 | wn | ⊢ ¬ 𝑥 <ℝ 𝑦 |
| 16 | 15 6 0 | wral | ⊢ ∀ 𝑦 ∈ 𝐴 ¬ 𝑥 <ℝ 𝑦 |
| 17 | vz | ⊢ 𝑧 | |
| 18 | 17 | cv | ⊢ 𝑧 |
| 19 | 7 18 8 | wbr | ⊢ 𝑦 <ℝ 𝑧 |
| 20 | 19 17 0 | wrex | ⊢ ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 |
| 21 | 10 20 | wi | ⊢ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) |
| 22 | 21 6 1 | wral | ⊢ ∀ 𝑦 ∈ ℝ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) |
| 23 | 16 22 | wa | ⊢ ( ∀ 𝑦 ∈ 𝐴 ¬ 𝑥 <ℝ 𝑦 ∧ ∀ 𝑦 ∈ ℝ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) ) |
| 24 | 23 5 1 | wrex | ⊢ ∃ 𝑥 ∈ ℝ ( ∀ 𝑦 ∈ 𝐴 ¬ 𝑥 <ℝ 𝑦 ∧ ∀ 𝑦 ∈ ℝ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) ) |
| 25 | 13 24 | wi | ⊢ ( ( 𝐴 ⊆ ℝ ∧ 𝐴 ≠ ∅ ∧ ∃ 𝑥 ∈ ℝ ∀ 𝑦 ∈ 𝐴 𝑦 <ℝ 𝑥 ) → ∃ 𝑥 ∈ ℝ ( ∀ 𝑦 ∈ 𝐴 ¬ 𝑥 <ℝ 𝑦 ∧ ∀ 𝑦 ∈ ℝ ( 𝑦 <ℝ 𝑥 → ∃ 𝑧 ∈ 𝐴 𝑦 <ℝ 𝑧 ) ) ) |