Archive for the ‘Germany’ Category

Happy π day!

Sunday, March 14th, 2010

Today is March 14th, aka pi day, a day celebrating one of the most important numbers in mathematics – π.

Since I happened to be in Germany today, I celebrated π day with my brother and his wife by making 2π — a yummy beef pie for dinner and a chocolate pie for dessert.

 Beef pie for pi day

For dessert we decided to make the pie even more meaningful and decorate the pie with the first few digits of π, resulting in a delicious, and informative pie:

Chocolate pi with digits!

More photos are available on Flickr and Facebook.

In other news, I’ll be arriving in Israel on Tuesday. If you want to meet me, let me know…

German voyage, Ill return

Friday, May 23rd, 2008

As promised, here are the chronicles of my German visit.

The visit started with a flight from Lisbon to Saarbrucken via Palma de Mallorca. It’s been quite a while since I’ve flown without frequent flyer benefits: No lounge, no special check-in. It was quite a shock to sit on the uncomfortable terminal chairs with no Internet access, but I managed. The flights themselves were surprisingly comfortable. Due to the fact I was flying on a low-cost carrier, I could book seat 1A, which is a regular economy seat, just in the front of the plane and with much more legroom. As luck would have it 1B was vacant on both flights, and on the second one 1C was vacant too, leaving me with a whole row to myself. Onboard service included a sandwich and free soft and hot drinks. All in all, a very positive experience, comparable even to “Europe Select” (business class) on KLM.

Between the flights, I ate at KFC at PMI, was surprised to see they offered Coke and not Pepsi, and French Fries instead of Mashed Potatoes, but the chicken was more or less the same. They also talked Spanish, but that I’m used to from KFC in the US too.

Saarbruecken airport is very small, serving mostly general aviation. It has exactly two gates and two baggage belts, and the passengers walk from the airstairs to the terminal. No border control was needed, and in less than half an hour from landing I was outside and picked up.

Later that night came the shock: The vacation apartment we were staying at did not have basic necessities: No Internet access, and even no phone! This left me without any form of communication with the outside world. In the following days, my outside communications were strictly monitored and limited, and thus no blog updates, among other things.

What we did do in the following days was play lots of boardgames I brought, and go touring in several towns in Germany and beyond.

The first day was all spent playing boardgames and resting. The next day we went to the northern Mosel valley and visited the tourist town of Cochem and Eltz Castle. This was not the original plan, but the road to the southern Mosel valley was closed for bicycles only for a “bicycle day”. I could not help noticing the contrast between that and what happened recently in San Francisco, where the city was sued by car owners for a plan to dedicate more bicycle lanes.

On the third day we went to Luxembourg, capital of Luxembourg.  On the way we passed the city of Schengen, which is known for the Schengen treaty for open borders in Europe. This leads to the anomaly that Luxembourg is in Schengen, while Schengen is in Luxembourg.  The city itself houses an impressive castle and “casemates” — ancient city fortifications. Another useful feature is the free municipal WiFi all over the city and the impressive views.

The fourth day was spent in the city of Heidelberg, known as the home of the first university in Germany, and well, another castle. The castle houses the largest wine barrel in the world, and a museum of German pharmacies.

The last day was spent packing and playing boardgames, and the day after was spent flying back. The route was STR-AMS-MSP-SFO.  We left home at 6am towards  Stuttgart airport, where I was upgraded to business class on the two short segments. The flights were comfortable, but the illness I began developing in Lisbon has intensified, and I spent the flights coughing and aching, especially the last one. The first class flight attendant was very nice and repeatedly offered me more tea, until we finally arrived at the airport. Finally I took the shuttle home and went to sleep.

At home, I checked my newly repaired laptop and some boardgames I’ve ordered and made a doctor’s appointment, where I’m headed right now.

My talks at Dagstuhl

Friday, October 26th, 2007

My Dagstuhl Nametag (October 2007)Yesterday I have given my planned talk at the Dagstuhl seminar about Selection Games and Deterministic Lotteries ( it’s always good to have an oxymoron in your titles). The talk went well and people were quite interested, given that many of the reviewers in the AAMAS conference where I submitted this paper were in the audience, I think my chances are good.

However, what I really wanted to talk about are the talks I gave today. Today we had a rump session, which is a special session where anyone can give 5 minute talks on any topic he or she wishes. Out of six talks, I gave two. One of the talks was about my work-in-progress regarding the manipulation of academic conferences.

The second talk of mine was humorous, and talked about manipulating the seating arrangements in Dagstuhl. Recall that researchers are seated randomly for meals in order to facilitate communication. My talk was a joke about this issue. If you are interested, take a look at the talk slides, posted exclusively on my blog. The issues of Manipulation, Bribery and Control are common considerations in the world of voting, all photos were taken during the seminar with my iPAQ camera.

Now I’m back at my brother’s house until Sunday when I am going to fly FRA-EWR-SFO and return to Stanford.

A paper with Vince

Thursday, October 25th, 2007

Dagstuhl Seminar group pictureI am having a good time at Dagstuhl Seminar 07431 on Computational Issues in Social Choice. Almost all talks are very interesting and I had some good conversations with some of the people here.

On Tuesday there was an open discussion about complexity of voting. While participating in this discussion, it became clear to me that there is something very wrong with most of the existing works on complexity of manipulating elections, and only very few papers dealt with the problem in the approach I consider more correct.

[If you are not interested in details about my research, skip the next two paragraphs]

It turned out that the principal authors of two of these papers are here at the seminar. I spent the night* between Tuesday and Wednesday thinking about this problem, and on Wednesday morning I had a developed idea. After telling Vince about it, he reminded me of the general Gibbard theorem, a corollary of which removes any hope of pursuing my crypto idea.

So, I let go of the crypto direction, and instead considered voting under partial information. There was limited work done on the subject, and I had some good ideas on how to model the problem. On Wednesday after lunch I got Vince interested, and together we managed to prove two interesting impossibility results and have some very important observations regarding this problem. As it seems, this work is on the way to become a paper.

I am very happy to be able to write a joint paper with Vince Conitzer.  I have known him since the first conference I attended in my PhD, which, as luck may have it, was a Dagstuhl seminar. Since then, I have met him in every conference I have attended. He has published over 40 papers, even though he has just recently finished his PhD, some of them with groundbreaking results.

* The reason I am working nights is my partial adaptation to jet lag, I go to sleep after dinner at 19:00 and wake up at about 3:00, I get enough sleep and don’t miss any talks, even though I don’t really live in the right timezone.

Abflug nach Deutschland

Thursday, October 18th, 2007

Approximate flight path to Frankfurt(that is, departure to Germany for those of you who don’t know German)

Yes, I’m flying again, this today my itinerary is SFO-IAH-AMS-FRA (that’s San Francisco, Houston, Amsterdam, Frankfurt), and then a train to Saarbruecken. The plan is to fly to Germany for a conference and visit my brother on the way. I’m going to be there for 10 days. I’m all packed (well, except my laptop) and in an hour I’ll be boarding the shuttle to the airport to start my journey.

In order to qualify for platinum I need about 3000 more miles. If I do not get any other trip funded this year, I’m considering doing a mileage run to West Palm Beach or to Boston. In the case of Boston, I might want to stay there for up to a week. Honolulu is also an option, although more expensive and with less miles.

Handbag Only

Monday, July 16th, 2007

KLM 737-800Last week I flew back home with no luggage, with only a handbag. This was due to the fact that I left my luggage at my brother‘s house in Saarbrücken. I will pick the luggage up when I return to Dagstuhl (and my brother) in October.

However, then I will be flying from the US and back, and thus will be able to carry the luggage left at my brother’s house in addition to whatever luggage I fly with to the US.

So, how do you fly handbag only? I checked in for my flights the day before and printed out an electronic boarding pass. I then used this boarding pass to go directly to the gate and board the flight without even passing the checking counters. Even my Silver status was mentioned on the boarding pass, so I got to use priority boarding as well.

In the Amsterdam – Tel Aviv leg I was assigned a whole row, but shortly before departure the flight attendants had to move two children who sat near the emergency exit to my row.

Upon landing at Ben Gurion airport, I head directly outside and wait for a shared taxi that (after three hours) brought me home.

A night at the opera*

Sunday, July 8th, 2007

Tonight I went to see my sister in law, Osnat Kaydar perform the lead female role in the cantata Camina Burana by Carl Orff. I am not a big classical music fan (to say the least), but I enjoyed the show very much.

It turns out that the opening and closing movement of the piece called “O Fortuna” is very well-known from movie trailers and many other uses in popular culture. Here it is for your listening enjoyment:

This piece is actually a 1936 adaptation of a medieval collection of poems by the same name. The text is almost entirely in Latin, which means I understood it just as well any other in the audience. The performance was amazing and I couldn’t get the “O fortuna” out of my head for some time afterwards.

After the concert, we went to eat at a good steak restaurant in town, and then back to sleep. I have packed my luggage, which I will leave here until I return in October. Tomorrow I’m going to fly home with a handbag only.

* By the way, as I said, this was not an opera but a cantata, but I chose to bend the title a bit.

Mein Bruder in Saarbrücken

Friday, July 6th, 2007

My brother -- Ronen Altman KaydarToday I have left Schloß Dagstuhl on my way to visit my brother, Ronen Altman Kaydar, who lives in Saarbrücken.

I arrived by taxi all the way from Dagstuhl. There were two other passengers in the taxi who were en route to Paris by the new TGV train. As we are all game theorists, we split the fare unevenly using the Nash Bargaining solution (yes, it’s the same Nash), so I paid €9 while the two others split the remaining €48 bill evenly.

I’ll now answer the question I was asked several times during the conference: What is my brother doing in this unknown corner of Germany? Well, the short answer is: translating English tour guides to Hebrew.

However, this has nothing to do with the reason for him being in Germany. He’s there because his wife, Osnat Kaydar, is an Opera singer, and studies at an opera school here. Tomorrow I am going to attend one of her concerts, so stay tuned.

Excursion to Völklinger Hütte

Wednesday, July 4th, 2007

Today after lunch there was a break from conference sessions. Conference participants were encouraged to participate in an excursion to an old ironworks, where iron ore and coal is converted into pig iron, which is the basis for the manufacture of steel.

In the tour, which took place outdoors in the rain, we saw the various steps in the production of steel. Our guide took her work seriously, while we joked about how hard is it to work in the “industry”.

It turns out that parts of the old ironworks were converted into exhibition halls. Today, there is an exhibition titled “Genius I” about the inventions of man from prehistory until today. It begins with an exhibit of prominent inventors and inventions. Some are reasonable such as the Wheel and Galileo Galilei, but some were more German-centric, such as Beer, and several German inventors.

The rest of the exhibition was very similar to any old science museum. I was not very impressed. As our time was limited, we had to leave quite early, so I didn’t see much more of the exhibition.

Photos were shot at the ironworks tour, but I cannot publish those online. I will get them later in the conference.

Dagstuhl day 1

Monday, July 2nd, 2007

Dagstuhl logoFirst day of the Dagstuhl seminar is now over. This is a good opportunity to tell you more about this unique place.

The idea of Dagstuhl seminars is to bring top computer scientists in a particular field from around the world and have them communicate with each other and do research. This communication is promoted by several means: First, all participants stay in the same building with hotel-style accommodations. Further, there is a coffee room, game rooms, a piano room and more informal activities to allow people to communicate. However, the most direct effort to promote communication is the random seating during lunch. The idea is to force people to talk with people outside their own narrow field of research.

Today I also gave my talk titled “An Axiomatic Approach to Personalized Ranking Systems“. Several people gave me compliments about my talk and many asked questions both during and after the talk. Also, it turned out that we are not the only ones mining eBay for reputation data, which means we might be able to get the data from someone else instead of gathering it ourselves.

At dinner I was seated with several people I know, and one person from Stanford who I didn’t know before. We had a nice conversation, and we have then retired to our rooms. There are no formal plans for the evening, so I plan to go online and maybe look around the premises here at Dagsuthl. All in all, I like it here.