Description: The implication between two sentences of propositional calculus is encoded by concatenating the two sentences and appending a two at the end. (Contributed by Thomas van Maaren, 21-Aug-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-propimp | ⊢ prop→ = ( 𝑥 ∈ V , 𝑦 ∈ V ↦ ( ( 𝑥 ++ 𝑦 ) ++ 〈“ 2 ”〉 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cpropimp | ⊢ prop→ | |
| 1 | vx | ⊢ 𝑥 | |
| 2 | cvv | ⊢ V | |
| 3 | vy | ⊢ 𝑦 | |
| 4 | 1 | cv | ⊢ 𝑥 |
| 5 | cconcat | ⊢ ++ | |
| 6 | 3 | cv | ⊢ 𝑦 |
| 7 | 4 6 5 | co | ⊢ ( 𝑥 ++ 𝑦 ) |
| 8 | c2 | ⊢ 2 | |
| 9 | 8 | cs1 | ⊢ 〈“ 2 ”〉 |
| 10 | 7 9 5 | co | ⊢ ( ( 𝑥 ++ 𝑦 ) ++ 〈“ 2 ”〉 ) |
| 11 | 1 3 2 2 10 | cmpo | ⊢ ( 𝑥 ∈ V , 𝑦 ∈ V ↦ ( ( 𝑥 ++ 𝑦 ) ++ 〈“ 2 ”〉 ) ) |
| 12 | 0 11 | wceq | ⊢ prop→ = ( 𝑥 ∈ V , 𝑦 ∈ V ↦ ( ( 𝑥 ++ 𝑦 ) ++ 〈“ 2 ”〉 ) ) |