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Description: Double syllogism inference combined with contraction. (Contributed by BTernaryTau, 29-Sep-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | syl2anc2.1 | ⊢ ( 𝜑 → 𝜓 ) | |
| syl2anc2.2 | ⊢ ( 𝜓 → 𝜒 ) | ||
| syl2anc2.3 | ⊢ ( ( 𝜓 ∧ 𝜒 ) → 𝜃 ) | ||
| Assertion | syl2anc2 | ⊢ ( 𝜑 → 𝜃 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | syl2anc2.1 | ⊢ ( 𝜑 → 𝜓 ) | |
| 2 | syl2anc2.2 | ⊢ ( 𝜓 → 𝜒 ) | |
| 3 | syl2anc2.3 | ⊢ ( ( 𝜓 ∧ 𝜒 ) → 𝜃 ) | |
| 4 | 1 2 | syl | ⊢ ( 𝜑 → 𝜒 ) |
| 5 | 1 4 3 | syl2anc | ⊢ ( 𝜑 → 𝜃 ) |