October 11th-12th

Palermo, Italy

Celebrating the 60th birthday of

Pino Rosolini

96th Peripatetic Seminar on Sheaves and Logic

October 11th-12th, 2014, Palermo, Italy


Celebrating the 60th birthday of Pino Rosolini


The 96th PSSL took place in Palermo, on the weekend of October 11th-12th, 2014, at the Dipartimento di Matematica e Informatica, via Archirafi 35, Palermo, Italy.

The 96th PSSL gave us the opportunity to celebrate the 60th birthday of Pino Rosolini, who has contributed to PSSLs since 1980 (16th PSSL meeting, Oxford, May 17th-18th 1980).

What is a PSSL?

Citing from PSSL93 website, "the PSSLs are a long-running series of meetings, usually held over a weekend at a university in Europe. Talks cover all aspects of category theory and its applications. The working atmosphere is informal, e.g. talks are usually short and may be about work in progress. The name is a (charming) historical relic - 'Peripatetic Seminar on Sheaves and Logic' - but most talks are not about sheaves or logic."

A curiosity: the 96th PSSL is the southernmost PSSL meeting ever held.

Organizing committee


We gratefully acknowledge financial support from:                        







A greating card from Professor Dana Scott here.


Some conference pictures can be found here.






SATURDAY 11th October
9:00 Welcome and opening Welcome address from the Head of Department, Professor C. Trapani
9:30 M. Hyland Finitary polynomials
10:00 D. McCarty What is logical truth?
10:30 Z. Janelidze Normal categories and duality
11:00 Coffee break
11:30 D. Bourn A conceptual approach to nilpotent objects in the Mat'cev context
12:00 M. Clementino On the representability of actions for topological algebra
12:30 T. van der Linden Algebraically coherent categories: definition, examples and basic properties
13:00 Lunch break
15:00 M. Fiore On the Functional Representation of Abstract Clones
15:30 J. Frey Enriched Pitts Functors as a framework for iteration and factorization of realizability and sheaf constructions
16:00 S. Maschio Models of IZF in Subtoposes of Nested Realizability Toposes
16:30 M.-E. Maietti Categorical Structures for the Foundation of Constructive Mathematics
17:00 Coffee break
17:30 M. Sobral Some remarks on descent for Priestley spaces
18:00 M. Dostal Characterising sifted weights
18:30 A. Simpson The random topos
SUNDAY 12th October
9:00 M. Gran Quandles, closure operators and factorization systems
9:30 P. North Moore Factorization Systems
10:00 F. Orsanigo Fibrational Parametricity
10:30 Coffee break
11:00 E. Robinson Type Structure and Logical Relations
11:30 J. Kock Point­-free topology and Hochster duality in derived categories
12:00 D. Rodelo A criterion for reflectiveness of normal extensions with an application to monoids
12:30 S. Lack Antipodes


Information for speakers

The lectures will be held in the Aula 7 (Lecture Room 7) of the Department of Mathematics and Computer Science. The room has a reasonably-sized blackboard, data projector and a overhead projector. Please let the organizers know what you would prefer to use for your presentation.







Name Affiliation
Dominique Bourn L.M.P.A. Université du Littoral, F.
Francesca Cagliari Università di Bologna, IT.
Alan Cigoli Università di Milano, IT.
Maria Manuel Clementino Universidade de Coimbra, PT.
Alex Corner University of Sheffield, UK.
Matej Dostal Czech Technical University in Prague, CZ.
Marcelo Fiore University of Cambridge, UK.
Jonas Frey University of Cambridge, UK.
Nicola Gambino University of Leeds, UK - Università di Palermo, IT.
Marco Geraci Università di Palermo, IT.
Enrico Ghiorzi University of Cambridge, UK.
Marino Gran Université Catholique de Louvain, BE.
Martin Hyland University of Cambridge, UK.
Zurab Janelidze Stellenbosch University, ZA.
Peter Johnstone University of Cambridge, UK.
Stefano Kasangian Università di Milano, IT.
Joachim Kock Universitat Autònoma de Barcelona, ES.
Steve Lack Macquarie University, AU.
Fred E. J. Linton Wesleyan University, USA.
David McCarty Indiana University, USA.
Maria Emilia Maietti Università di Padova, IT.
Sandra Mantovani Università di Milano, IT.
Nelson Martins-Ferreira Instituto Politécnico de Leiria, PT.
Samuele Maschio Università di Padova, IT.
Giuseppe Metere Università di Palermo, IT.
Andrea Montoli Universidade de Coimbra, PT.
Paige North University of Cambridge, UK.
Fabio Pasquali University of Bordeaux, F.
Federico Orsanigo Strathclyde University, UK.
Linda Pizzamiglio IT.
Edward Prior University of Sheffield, UK.
Edmund Robinson Queen Mary, University of London, UK.
Diana Rodelo Universidade do Algarve, PT.
Pino Rosolini Università di Genova, IT.
Alex Simpson University of Edimburgh, UK.
Manuela Sobral Universidade de Coimbra, PT.
Lurdes Sousa Polytechnic Institute of Viseu / CMUC, PT.
Settimo Termini Università di Palermo, IT.
Aldo Ursini Università di Siena, IT.
Tim Van der Linden Université Catholique de Louvain, BE.
Jaap van Oosten University of Utrecht, NL.
Enrico M. Vitale Université Catholique de Louvain, BE.





Practical Information

Here you find suggestions and advices for traveling to Palermo, finding an accommodation and the location of the conference.

Getting to Palermo by plane

The best way to reach Palermo is by plane. We recommend using

Other Sicilian airports of interest are:

There are many flights to Falcone-Borsellino International Airport from Rome, Milan and other Italian towns.  It is also possible to find direct flights to Palermo from many European towns, operated by either low-cost or national/private companies. Visit the  Falcone-Borsellino International Airport web site for more information.

Transportation from and to Falcone-Borsellino Airport

Getting to Palermo by Boat

Palermo is well connected by boat to Naples, Livorno, Civitavecchia, Genova and other Italian towns. For more information you can visit the web sites of the following sailing companies:

Grandi Navi Veloci, Grimaldi Group Napoli S.N.A.V., Siremar, Tirrenia.

Getting to Palermo by Train

Sicily, and Palermo, can be reached by train from most of Italian towns, but be prepared for a long trip... Normally, if you leave from Rome or Milan, you must take a train that brigs you to Reggio Calabria or Villa San Giovanni, then get the Ferry to Messina, and take again a train to get to Palermo. 

For more information you can visit the Italian Railways website:

The Conference Location

Directions to the Dipartimento di Matematica e Informatica. The conference will be held at the Department of Mathematics and Informatics of the Università degli Studi di Palermo. The department building is n.34 of via Archirafi. You will get there probably coming from the railway station square (Piazza Giulio Cesare), walking down via Lincoln until it crosses with via Archirafi. Along via Archirafi, on the left, you first meet Hotel Villa Archirafi, then the various buildings of some Departments of the University of Palermo (see the main picture above in this page). This is an historical site of Palermo University, which nowadays is spread all over the town. Behind these buildings, you can barely see the botanic garden of Palermo.

The Department of Mathematics and Informatics is located at n.34 of via Archirafi. A map of the area is available here.

Directions to the lecture room. The lectures will be held in Aula 7 (Lecture Room 7), which is located on the ground floor of the department. After entering the building, go through the central hall (where you can find vending machines) and then turn left.

Finding an Accommodation

Palermo is a major touristic attraction in Italy, but October is surely not peak season. In fact, the weather is usually fine, with an average of 20 oC, and few raining days, usually at the end of the month.
The conference venue is not far away from the city centre, where you can find a variety of Hotels. To be considered also the Bed and Breakfasts: very good deals can be found in this period of the year. Down here we gathered some suggestions.





About Palermo

(Freely extracted from the Wikipedia).
Palermo [palεrmo] (Palermu [palεɽmu] in Sicilian) is a city of the south of Italy, on the northwestern coast of the island of Sicily. Capital of the autonomous Region of Sicily, it is the fifth Italian town by population after Rome, Milan, Naples and Turin. The city is noted for its history, culture, architecture and gastronomy, playing an important role throughout much of its existence; it is over 2,700 years old.
The city was founded in 734 BC by the Phoenicians, who named it "Zyz" ("Flower" or "Shining"). The Greeks named the city "Panoremus" meaning "complete harbour". Palermo was part of the Roman Republic/Empire, and eventually part of the Byzantine Empire, for over a thousand years. From 827 to 1071 it was under Arab rule during the Emirate of Sicily, when it first became a capital. The Arabs corrupted the Greek name into Balarm, the root for its present-day name. Following the Norman conquest, Palermo became capital of a new kingdom (from 1130 to 1816), the Kingdom of Sicily. Eventually it would be united with the Kingdom of Naples to form the Kingdom of Two Sicilies until the Italian unification of 1860. Today Palermo, with an urban area population of more than 850000, is Sicily's cultural, economic and touristic capital. It attracts many tourists for its nice Mediterranean weather, its renowned gastronomy and restaurants, its Romanesque, Gothic and Baroque churches, palaces and buildings, and its nightlife and music.

Just outside Palermo, is located one of the greatest extant examples of Norman architecture in the world: the Cathedral of Monreale. It was begun in 1174 by William II, and in 1182 the church, dedicated to the Assumption of the Virgin Mary, was, by a bull of Pope Lucius III, elevated to the rank of a metropolitan cathedral.

The church is a national monument of Italy and one of the most important attractions of Sicily.





Satellite event

Friday Seminar

On Friday, we organized a special Seminar, satellite event of the PSSL96. Just as the PSSL, it was held in the Aula 7 (Lecture Room 7) of the Department of Mathematics and Computer Science. The talks were held according to the following scheme:


FRIDAY 10th October
15:00 A. Ursini Ideal theory in categorical and universal algebra: an update
15:30 N. Martins-Ferreira Internal reflexive graphs with respect to pointed endofunctors
16:00 L. Sousa Towards a calculus of fractions concerning Kan-injectivity


PSSL pre-registration started on Friday evening, at 16.30, right after the last talk of the seminar, and lasted up to 18.00 approx.