Timeline for infinitary logic and partial fixed point logic
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 14, 2014 at 17:43 | comment | added | Joel David Hamkins | @NoahS, the advantage of your method, even though it uses infinitely many variables, is that it works in any language (assuming $=$ is available), whereas I needed something special about the language. | |
| Apr 14, 2014 at 17:38 | comment | added | Noah Schweber | Yeah, I deleted it because it used infinitely many variables and I didn't see a way to fix it. This is very nice! | |
| Apr 14, 2014 at 13:23 | comment | added | Joel David Hamkins | If one objects that the language here is infinite, then we may use instead the language with one constant $0$ and a successor operation $S$, defining the class of finite models $M$ for which the least $n$ for which $S^n(0)=0$ is in $X$. | |
| Apr 14, 2014 at 13:09 | comment | added | Joel David Hamkins | We could also insist that the models have only two elements, and so what we really have is a partition of the natural numbers into at most two pieces, depending on how the constants are interpreted. | |
| Apr 14, 2014 at 12:39 | history | answered | Joel David Hamkins | CC BY-SA 3.0 |