Timeline for Why $A \cap B = \widehat{\widehat{A}\cup \widehat{B}}$ does not holds for the class of Recursively Enumerable Languages?
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 9, 2016 at 12:33 | vote | accept | Romy | ||
| Jan 9, 2016 at 11:07 | comment | added | chi | @Romy Yes, that's fine. Also, if it's closed under intersection and complement, then it's closed under union. A formulaic alternative: complement-closure implies (union-closure iff intersection-closure). | |
| Jan 9, 2016 at 8:06 | comment | added | Romy | Thanks a lot, I used implication incorrectly here.The correct claim would be "If a class is closed under Union & Complement then it must also be closed under Intersection and consequently under Difference." Right? | |
| Jan 9, 2016 at 7:36 | history | answered | D.W.♦ | CC BY-SA 3.0 |