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The IT University of Copenhagen

Peripatetic Seminar on Sheaves and Logic


March 2-3, 2002

ITU, Glentevej 67

The 76th meeting of the Peripatetic Seminar on Sheaves and Logic (PSSL) will be held at the IT-University of Copenhagen (IT-C) over the weekend of 2-3 March 2002.

As usual, we welcome talks on sheaves, category theory, logic, and related areas such as applications in (theoretical) computer science. As the meeting is informal in nature, talks on work in progress are also welcome.

Travel Information

All pricing information is given in Danish Kroner DKK. One Euro is about DKK 7.50.

Copenhagen is located on the east coast of the island Sjaelland. The site Wonderful Copenhagen is the official website of the tourist board of Copenhagen and gives you information about this wonderful city in the north of Europe.

Copenhagen Airport (airport code CPH) is a major European airport with direct flights to most larger European cities. From the airport it takes less than 15 minutes by train to reach the centre of the city. Trains stop among others at the main station (Hovedbanegård). Tickets to the city centre (3 zones) should be bought before boarding the train and cost DKK 21. Trains leave about every 20 minutes.

There are direct trains to Copenhagen from Sweden and from Germany. Day trains from Germany leave from Hamburg Central Station and take 4 1/2 hours (the trains take the ferry between Puttgarden and Rødby). There are also direct night trains from and to the Ruhrgebiet and southern Germany. The German rail server provides travel information in English. Copenhagen Central Station is known as Kobenhavn H. For example, a saver return ticket from anywhere in Germany to Copenhagen costs 152 Euro (182 Euro if one uses ICE trains). Up to 4 more people can join to travel together and pay only 76 Euro (91 Euro respectively) each.

For travel information from Sweden we refer to the timetables at (we had some problems with that site) and


All pricing information is given in Danish Kroner DKK. One Euro is about DKK 7.50. Please contact Carsten Butz if you need assistance.

We suggest that you make a reservation in Hotel Leda:
Leda Hotel
Svanevej 6
2400 København NV
Tel: +45 35 83 12 22
Fax: +45 35 83 12 24
Payment: American Express, Cash, Check, Dankort, Diners Club, Eurocard, MasterCard, VISA
Rate: DKK 600
Please mention that you will be visiting the IT-University (IT-højskole) to get the discounted rate of DKK 600 for a single room. The rate is a good deal for Copenhagen. The hotel is in walking distance from the University. Travel details will follow soon.

If your budget is tight, there are a number of other options:
Hotel Jørgensen
Rømersgade 11
1362 København K
Tel: +45 33 13 81 86
Fax: +45 33 15 51 05
Payment: Cash, Dankort, Eurocard, MasterCard, VISA
Rates start at DKK 525.
A small hotel close to Nørreport Station. Central, with good bus connection to the IT-University.
Hotel Nebo
Istedgade 6
1650 København V
Tel: +45 33 21 12 17
Rates start at DKK 420.
A small hotel close to central station. Good bus connection to the IT-University. The rooms are clean but very simple and show some wear.

For those with a very tight budget there is also the option to stay in the youth hostel. There are a number of them in the city. The one closest to the IT-University is the following.
Copenhagen Bellahøj DanHostel
Herbergvejen 8
2700 Brønshøj
Tel: +45 38 28 97 15
Fax: +45 38 89 02 10
Rates in the dormatory start at DKK 90, those in double rooms at about DKK 250. You need a membership card and may want to rent linen. This place opens March 1, but reservations can be made before.

Finding Your Way in Copenhagen

Language: Danes are helpful and most Danes speak English quite well. This also applies to bus drivers, once they have recovered from being approached in English. The pronunciation of the Danish letters æ and ø comes close to the German ä and ö or the English e in egg and i in first. The Danish å is pronunced like the o in lord. The correct transcription of these letters is ae, oe, and aa, although you often find that ø is transcribed by o as in IT-hojskole.

Local Transport: We wrote a short summary on public transport ( here in Copenhagen which provides information about local buses and trains and the type of tickets you can buy. Don't be scared by the length of it, the information is very detailed. All participants got a (surface) letter which includes a small town map and a print-out of the file above.

The following map taken from our homepage (How to find us) shows the neighbourhood of the IT-University and the busstop of bus 250S coming from the airport.

The following webpages provide general information on Copenhagen:

Food and Dining: Please note that most shops close Saturday afternoon. However, most small grocery stores are open during the evening hours and on Sunday so that you can get basic supply of fresh fruits and drinks.

On Nørrebrogade you will find a number of small places offering good food. Many are take-outs and based on Turkish or Persian cuisine.

The following is a list of places close suggested by staff members here at the university:
Close to IT-University
Cafe Castro
Nørrebrogade 209
2200 København N
Phone: 35 85 35 85
This is also the place where we meet on Friday evening, see below.
Cafe Ultimatum
Nordre Fasanvej 267
2200 København N
Phone: 35 81 18 84
Very close to Hotel Leda. Good and big warm sandwich and Italian food.
Cafe Ae
Frederikssundsvej 7
2400 København N
Phone: 35 81 11 77
Samosa House
Frederikssundsvej 35
Phone: 38 10 88 85
Pakistan/Indian take-out.
In the centre ...
Restaurant Frontpage
Sortedam Dossering 21, kld.
2200 København N
Phone: 35 37 38 29
A very good place. The two-course menue costs DKK 198.
Pasta Basta
Valkendorfsgade 22
1151 København K
Phone: 33 11 21 31
Cafe Ketchup Pilestræde
Pilestræde 19
1112 København K
Phone: 33 32 30 30
Cafe Sebastopol
Sankt Hans Torv 32
2200 København N
Phone: 35 36 30 02
Ristorante Quattro Fontaine
Guldbergsgade 3
2200 København N
Phone: 35 39 39 31
Det Lille Apotek
Store Kannikestræde 15
1169 København K
Phone: 33 12 56 06
Traditional Danish lunch.
Nyhavns Færgekro
Nyhavn 5
1051 København K
Phone: 33 15 15 88


On Friday evening we will meet in Cafe Castro, Nørrebrogade 209, 2200 København N, phone: 35 85 35 85. The cafe is located between Esromrade and Hillerørdgade (from Hotel Leda this is towards the city centre), and some of us will be there starting at 7:30 pm.

There will be coffee and tea available before the first talks on Saturday and on Sunday.

09:25 - 09:30 welcome
09:30 - 10:15 T. Leinster A. Kock
10:15 - 10:45 coffee/tea coffee/tea
10:45 - 11:30 E. Cheng M. Menni
11:30 - 12:15 R. Milner J. Adamek
12:15 - 13:30 lunch lunch
13:30 - 14:15 J. Velebil
14:15 - 15:00 H. Porst
15:00 - 15:30 coffee/tea
15:30 - 16:15 A. Simpson
16:15 - 17:00 C. Butz


Jiri Adamek (Braunschweig):Varieties of algebras as categories
Eugenia Cheng (Cambridge):Expressing trees as Kelly-Mac Lane graphs
Sjoerd Crans (Strasbourg):-
Pieter Hofstra (Utrecht):-
Tom Leinster (Cambridge):Triangulated categories and n-categories
Matias Menni (Genova):(More) \new-quantifiers
Robin Milner (Cambridge):Bigraphs
Hans Porst (Bremen):Presentability in categories of coalgebras
Alex Simpson (Edinburgh):First-order set theory in an elementary topos
Jiri Velebil (Braunschweig):Final coalgebras for arbitrary endofunctors
Local Participants:
Lars Birkedal:-
Carsten Butz:First-order set theory in a category of classes
Thomas Hildebrand:-
Anders Kock (Århus):The stack quotient of a groupoid
Volodya Shavrukov:-
Noah Torp-Smith:-

Organising Committee

We are assisted by administrative officer Benthe Heldbjerg Hansen

Please direct all correspondence to Carsten Butz:


The venue of the seminar is the IT-University of Copenhagen. Our postal address is

IT-University of Copenhagen
Glentevej 67
2400 Copenhagen NV


The following announcements and calls for participation were sent out at the categories mailing list. Please feel free to distribute them to people who might be interested in joining the seminar.