Description: Predecessor is a subset of its successor. (Contributed by Peter Mazsa, 12-Jan-2026)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | press | ⊢ ( 𝑁 ∈ Suc → pre 𝑁 ⊆ 𝑁 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | sssucid | ⊢ pre 𝑁 ⊆ suc pre 𝑁 | |
| 2 | sucpre | ⊢ ( 𝑁 ∈ Suc → suc pre 𝑁 = 𝑁 ) | |
| 3 | 1 2 | sseqtrid | ⊢ ( 𝑁 ∈ Suc → pre 𝑁 ⊆ 𝑁 ) |