Sixth Symposium on Compositional Structures (SYCO 6)

University of Leicester, UK
16-17 December 2019

The Symposium on Compositional Structures is a regular series of interdisciplinary meetings aiming to support the growing community of researchers interested in the phenomenon of compositionality, from both applied and abstract perspectives, and in particular where category theory serves as a unifying common language. We welcome submissions from researchers across computer science, mathematics, physics, philosophy, and beyond, with the aim of fostering friendly discussion, disseminating new ideas, and spreading knowledge between fields. Submission is encouraged for both mature research and work in progress, and by both established academics and junior researchers, including students.

Submission is easy, with no format requirements or page restrictions. The meeting does not have proceedings, so work can be submitted even if it has been submitted or published elsewhere. You could submit work-in-progress, or a recently completed paper, or even a PhD or Masters thesis.

While no list of topics could be exhaustive, SYCO welcomes submissions with a compositional focus related to any of the following areas, in particular from the perspective of category theory:

This new series aims to bring together the communities behind many previous successful events which have taken place over the last decade, including Categories, Logic and Physics, Categories, Logic and Physics (Scotland), Higher-Dimensional Rewriting and Applications, String Diagrams in Computational, Logic and Physics, Applied Category Theory, Simons Workshop on Compositionality, the Yorkshire and Midlands Category Theory Seminar and the Peripatetic Seminar in Sheaves and Logic.

This event follows SYCO 1 in Birmingham, SYCO 2 in Strathclyde, SYCO 3 in Oxford, SYCO 4 in California, and SYCO 5 in Birmingham.

Invited speakers

Gabriella Böhm Jennifer Hackett
Wigner Research Centre for Physics, Budapest Department of Computer Science, University of Nottingham
A unified treatment of quantum symmetries Cost and compositionality

Best student presentation award

Maaike Zwart
Maaike Zwart
University of Oxford
Composite Theories, and how to use them to prove no-go theorems for distributive laws

PhD recruitment fair

This event will include a poster session advertising PhD opportunities in category theory and related disciplines. If you are interested in advertising PhD opportunities at your institution, please notify the local organizer Simona Paoli at, and come along to the meeting (or send a colleague or student) with a poster advertising your PhD opportunities. We expect significant participation from Masters students and final-year undergraduates who are considering applying for study in this area.

Important dates

All deadlines are 23:59 anywhere-on-earth on the given dates.


Some funding is available for Masters students, PhD students and junior researchers to attend. To apply for this funding, please send an email to Jamie Vicary at by Monday 2 December with subject line "SYCO 6 funding application", giving a brief summary of your current status and funding required. Results of the funding application will be notified to applicants on Tuesday 3 December.


All talks are in the Bennett Link Lecture Theatre, wine reception and PhD-fair are in the Charles Wilson Belvoir Park Lounge on the second floor. You can find these locations on the map under local information.

In talks with multiple authors the speaker is indicated with a star *.

Time Monday 16 December Tuesday 17 December
9:30–10:00 Jennifer Hackett, "Cost and Compositionality" (invited talk)
10:30–11:00 REGISTRATION (Bennett Building) Quanlong Wang, "An algebraic axiomatisation of ZX-calculus"
11:00–11:30 BREAK
11:30–12:00 Gabriella Böhm, "A unified treatment of quantum symmetries" (invited talk) Dorette Pronk* and Laura Scull, "New Results on Bicategories of Fractions Applied to Orbifolds"
12:00–12:30 Amar Hadzihasanovic, "Representable diagrammatic sets as a model of weak higher categories"
12:30–13:00 Filippo Bonchi, Robin Piedeleu*, Pawel Sobocinski and Fabio Zanasi, "Contextual Equivalence for Signal Flow Graphs" LUNCH
13:00–13:30 LUNCH
14:00–14:30 Drew Moshier and Steve Vickers*, "Cartesian bicategories and their Karoubi envelopes"
14:30–15:00 Morgan Rogers* and Jens Hemelaer, "Monoid Properties as Topos-Theoretic Invariants"
15:00–15:30 Vincent Wang, "Graphical Grammar + Graphical Completion of Monoidal Categories" BREAK
15:30–16:00 BREAK John Stell, "Mathematical Morphology on Graphs: The role of relations on hypergraphs."
16:00–16:30 Louis Parlant, "Monoidal Monads and Preservation of Equations" Guillaume Boisseau, "String diagrams for optics"
16:30–17:00 Maaike Zwart* and Dan Marsden, "Composite Theories, and how to use them to prove no-go theorems for distributive laws"
17:00–17:30 Callum Reader, "Probability Monads for Enriched Categories"
from 17:30 WINE RECEPTION AND PhD FAIR (Charles Wilson Building)

Conference photo


Although registration deadline has passed, late registrations are still accepted. Please register by filling out this form.


Amongst the participants where the following 52 people.

Local information

All talks will be held in the Bennett building, whose entrance is marked with a red star in the map below. Click here for a campus map and here for a list of restaurants nearby the university.


London Mathematical Society.


The intention is for SYCO to be a community meeting, where people have enough time to explain their ideas, and with a friendly and non-competitive atmosphere. To encourage this, in the event that more submissions are received of an acceptable standard than can be accommodated in the timetable, the programme committee may choose to defer some submissions to a future meeting, rather than reject them. This would be done based largely on submission order, giving an incentive for early submission, but would also take into account other requirements, such as ensuring a broad and inclusive scientific programme. Deferred submissions can then be re-submitted to any future SYCO meeting, where they will be prioritised for inclusion in the programme, and where they will not need to be re-reviewed. Meetings are held sufficiently frequently to avoid a backlog of deferred papers.


Submission will be by EasyChair, via the SYCO 6 submission page

Submissions should present research results in sufficient detail to allow them to be properly considered by members of the programme committee, who will assess their interest to the SYCO community. We encourage the submission of work in progress, as well as mature results. There are no proceedings, so work can be submitted even if it has been previously published, or has been submitted for consideration elsewhere. There is no specific formatting requirement, and no page limit, although for long submissions authors should be aware that reviewers will not be able to read the entire document in detail. Think creatively—you could submit a recent paper, draft notes of a project in progress, or even a recent Masters or PhD thesis.

If you have a submission which was deferred from a previous SYCO meeting, it will not automatically be considered for SYCO 6; you still need to submit it again through EasyChair. Such a submission will be prioritised for inclusion in the SYCO 6 programme. When submitting, append the words "DEFERRED FROM SYCO X" to the title of your paper, replacing "X" with the appropriate meeting number. There is no need to attach any documents.

Programme committee

Steering committee

The symposium is managed by the following people. If you have a general question about SYCO, or if you want to propose to host a future version, please get in touch with a member of the steering committee.

Local organizer

Simona Paoli, Roy Crole, Peter Guthmann, Andrew Smith

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