Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > MPE Home > Th. List > sb1 | Structured version Visualization version GIF version |
Description: One direction of a simplified definition of substitution. The converse requires either a dv condition (sb5 2418) or a non-freeness hypothesis (sb5f 2374). (Contributed by NM, 13-May-1993.) |
Ref | Expression |
---|---|
sb1 | ⊢ ([𝑦 / 𝑥]𝜑 → ∃𝑥(𝑥 = 𝑦 ∧ 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-sb 1868 | . 2 ⊢ ([𝑦 / 𝑥]𝜑 ↔ ((𝑥 = 𝑦 → 𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑))) | |
2 | 1 | simprbi 479 | 1 ⊢ ([𝑦 / 𝑥]𝜑 → ∃𝑥(𝑥 = 𝑦 ∧ 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 383 ∃wex 1695 [wsb 1867 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem depends on definitions: df-bi 196 df-an 385 df-sb 1868 |
This theorem is referenced by: spsbe 1871 sb4 2344 sb4a 2345 sb4e 2350 sb6 2417 bj-sb4v 31945 bj-sb6 31955 bj-sb3b 31992 wl-sb5nae 32519 |
Copyright terms: Public domain | W3C validator |