I have already voted. I have registered to vote by mail which is very convenient. I have voted exclusively for Democratic party candidates. I will probably continue to do so for a long time as the Republican party has shifted so far to the right. I think the Republican party has become Trumps’s party and that change has been deep and will be long lasting. I have not supported the Republican party for a long time and in my opinion it has taken a change for the worse.
I just upgraded to Ubuntu 18.04 from 16.04. 16.04 was ok. I have been on 18.04 for a few days with a smooth upgrade and no problems except a couple of minor glitches.
I think I wrote about having problems with electric power in a previous post. We have now replaced the fusebox so we should have better performance in that area. Happy Thanksgiving to everybody!
I haven’t posted here for a while. I have had as the title suggests had various problems. I have had a power outage then after I got that fixed My computer stopped working and then our internet went out. We ended up changing ISP’s which is good because the new one doesn’t have a data cap. Apparently the old one didn’t support our old modem. I got the computer working and I am posting this using the Linux operating system again. The problems I have had with this computer are related to hardware.
Happy Thanksgiving to everyone in the US. Recently I wrote about a problem I had with Linux. I think now that it is not related to Linux but was a hardware problem. In any case the problem has not repeated itself and I am glad.
I have recently had some trouble with Linux. Ubuntu wouldn’t load. I had to run fsck to fix it. I am not sure exactly what the problem was or what caused it. I may have similar problems. I will wait and see.
I have upgraded from Ubuntu 14.04 to 16.04. It made it easier to install polymake. So I installed it. It looks interesting. So far 16.04 is running smoothly for me.
I am using Linux as my main operating system for the first time. Before I had Chrome, before that Windows 7. It is OK. There are a few odd things like I have to watch Netflix on a Chrome browser and Hulu on Firefox but it is going well. I can run Sage on this computer without an emulator so in that sense it is an improvement over Windows. Also I don’t need antivirus software.
I have not posted for a while. One thing I think I mentioned a while back is computer problems. That has been dealt with to a degree that it should not be an obstacle to posting. I hope everyone is enjoying the holidays and that they will have a good 2016.
In my previous post “transitive sets” I discussed the idea that instead of all spherical sets being Ramsey, a set is Ramsey if its symmetry group of isometries is transitive. In this post I want to give a simple example of a configuration which is spherical but can’t be embedded into a set which has a transitive symmetry group of isometries.
The example comes from the paper “Transitive sets and cyclic quadrilaterals” by I. Leader,P.A. Russell and Mark Walters. It is here. In corollary 2 of the paper they prove the set $$((-1,0),(1,0),(a,\sqrt{1-a^2},(a,-\sqrt{1-a^2}))$$ where $a$ is transcendental does not embed into any transitive set. This type of set is called a kite.
If you could find a set which satisfies the above properties and prove it is Ramsey that would provide a counterexample to the hypothesis of the first paragraph. In any case this is a good example of a set which is spherical and can’t be embedded into a transitive set. I may continue this series of posts later.
