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Description: Restricted existential specialization, using implicit substitution. (Contributed by Glauco Siliprandi, 15-Feb-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | rspced.1 | ⊢ Ⅎ 𝑥 𝜒 | |
| rspced.2 | ⊢ Ⅎ 𝑥 𝐴 | ||
| rspced.3 | ⊢ Ⅎ 𝑥 𝐵 | ||
| rspced.4 | ⊢ ( 𝜑 → 𝐴 ∈ 𝐵 ) | ||
| rspced.5 | ⊢ ( 𝜑 → 𝜒 ) | ||
| rspced.6 | ⊢ ( 𝑥 = 𝐴 → ( 𝜓 ↔ 𝜒 ) ) | ||
| Assertion | rspced | ⊢ ( 𝜑 → ∃ 𝑥 ∈ 𝐵 𝜓 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | rspced.1 | ⊢ Ⅎ 𝑥 𝜒 | |
| 2 | rspced.2 | ⊢ Ⅎ 𝑥 𝐴 | |
| 3 | rspced.3 | ⊢ Ⅎ 𝑥 𝐵 | |
| 4 | rspced.4 | ⊢ ( 𝜑 → 𝐴 ∈ 𝐵 ) | |
| 5 | rspced.5 | ⊢ ( 𝜑 → 𝜒 ) | |
| 6 | rspced.6 | ⊢ ( 𝑥 = 𝐴 → ( 𝜓 ↔ 𝜒 ) ) | |
| 7 | 1 2 3 6 | rspcef | ⊢ ( ( 𝐴 ∈ 𝐵 ∧ 𝜒 ) → ∃ 𝑥 ∈ 𝐵 𝜓 ) |
| 8 | 4 5 7 | syl2anc | ⊢ ( 𝜑 → ∃ 𝑥 ∈ 𝐵 𝜓 ) |