Description: A syllogism inference from two biconditionals. (Contributed by NM, 5-Aug-1993)
Ref | Expression | ||
---|---|---|---|
Hypotheses | bitr2di.1 | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) | |
bitr2di.2 | ⊢ ( 𝜒 ↔ 𝜃 ) | ||
Assertion | bitr2di | ⊢ ( 𝜑 → ( 𝜃 ↔ 𝜓 ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | bitr2di.1 | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜒 ) ) | |
2 | bitr2di.2 | ⊢ ( 𝜒 ↔ 𝜃 ) | |
3 | 1 2 | bitrdi | ⊢ ( 𝜑 → ( 𝜓 ↔ 𝜃 ) ) |
4 | 3 | bicomd | ⊢ ( 𝜑 → ( 𝜃 ↔ 𝜓 ) ) |