Beppe Metere's Web Site

Research

My research interest are Category Theory and Categorical Algebra.

Popularisation of Mathematics and Science

Good actions. Algebraic and categorical perspectives. Notes from a lecture given at Stellenbosch University in April 2026.

A natural road to Sylow. A travel guide to group theory for second-year maths students. Course notes, April 2026.

The wise old scientist: a commentary on ethics, old age and science. Personalised services for the Elders. Discussing design options in an interdisciplinary and intercultural way. Villa Vigoni - 28th November - 2nd December 2022.

Algorithms and diagrammatic reasoning. Autonomous and Algorithmic Cultures: Responsibility in the Knowledge Production and its Applications. Villa Vigoni - 4th-8th November 2019.

Selected slides of research talks

The butterfly effect. Slides from CT&CatAlg, Workshop on the occasion of Enrico Vitale 60th birthday. Milan, September 2024.

Relative ideals in homological categories. Slides from a seminar at the University of Milan, March 22, 2024.

Groupal pseudofunctors. Slides from "New Trends in Hopf Algebras and Monoidal Categories, Turin, September 2022.

Some fibrational properties of normal monomorphisms Slides from "Algebra, Logic and Topology Seminar" C.M.U.C. July 2020.

Some thoughts on Yoneda's "regular spans" Slides from 5th Workshop on Categorical Methods in Non-Abelian Algebra, UCLouvain, July 2017.

Extension theory and the calculus of butterflies Slides from 96th Peripatetic Seminar on Sheaves and Logic, UCLouvain, January 2015.

How to get a snail from a butterfly Slides from 96th S.I.C., UCLouvain, July 2014.

Braided and symmetric internal groupoids Slides from CatAlg 2011, Gargnano del Garda.

In Italian

Archimede, appunti per un viaggio a Siracusa. Intervento tenuto nella classe 2H del Liceo Classico G. Carducci, Milano. (2024).

La googologia e la logica dei grandi numeri. Intervento in occasione del WLD2024, Palermo.

C' è un'età per la scienza? - Viaggio alla scoperta del rapporto tra attività di ricerca e invecchiamento. contenuto in dalla Società della Scienza, Palermo University Press (2025).

Un invito all'algebra categoriale. Seminario di Dipartimento del 8 giugno 2022.

Conferences (co)organized

ItaCa 2025 6th ItaCa Workshop, Milano, 2025.
CT&CatAlg Workshop on the occasion of Enrico Vitale 60th birthday, Milano, 2024.
PSSL108: Peripatetic Seminar on Sheaves and Logic, Terrasini, 2023.
CatAlg2022: Workshop in Categorical Algebra, Gargnano, 2022.
CT20->21: Category Theory Conference, Genova, 2021.
PSSL105: Peripatetic Seminar on Sheaves and Logic, Palermo, 2019.
CatAlg2018: Workshop in Categorical Algebra, Gargnano, 2018.
CatAlg2015: Workshop in Categorical Algebra, Gargnano, 2015.
PSSL96: Peripatetic Seminar on Sheaves and Logic, Palermo, 2014.
Aurelio2013: Conference in Memory of Aurelio Carboni, Milano, 2013.
CatAlg2011: Workshop in Categorical Algebra, Gargnano, 2011.
CatAlg2006: Workshop in Categorical Algebra, Milano, 2006.

Preprints and Accepted Papers

M. Mancini, G. Metere, F. Piazza Coherent and ideal actions in ideally exact categories, submitted (2025).
M. Mancini, G. Metere, F. Piazza On actions and split extensions in varieties of hoops: the case of strong section, accepted for the publication on Studia Logica (2026).
S. Kasangian, G. Metere and E. M. Vitale, Weak inverses for strict n-categories, unpublished (2010).
G. Metere, Homotopy pullbacks for n-categories, unpublished (2009).

Pubblished Papers

S. Lapenta, G. Metere, L. Spada Relative ideals in homological categories, with an application to MV-algebras, Theory and Applications of Categories, Vol. 41 no. 27 (2024).
A. S. Cigoli, M. Mancini, G. Metere, On the representability of actions of Leibniz algebras and Poisson algebras, Proceedings of the Edinburgh Mathematical Society , Volume 66 , Issue 4 (2023).
A. S. Cigoli, S. Mantovani, G. Metere, The third cohomology 2-group, Milan J. Math. (2023).
A. S. Cigoli, S. Mantovani, G. Metere, On pseudofunctors sending groups to 2-groups, Mediterr. J. Math. 20, 17 (2023).
A. S. Cigoli, S. Mantovani, G. Metere, E. M. Vitale, Fibred-categorical obstruction theory, Journal of Algebra 593 (2022).
D. Bourn, G. Metere, A note on the categorical notions of normal subobject and of equivalence class, Theory and Applications of Categories Vol. 36 No. 3 (2021).
A. S. Cigoli, S. Mantovani, G. Metere, Discrete and Conservative Factorizations in Fib(B), Applied Categorical Structures 29 (2020).
A. S. Cigoli, S. Mantovani, G. Metere, E. M. Vitale, Fibered aspects of Yoneda's regular span, Advances in Mathematics, 360 (2020).
S. Mantovani, G. Metere, E.M. Vitale, The snail lemma for internal groupoids, Journal of Algebra, 535 (2019).
P.-A. Jacqmin, S. Mantovani, G. Metere, E. M. Vitale, Bipullbacks of fractions and the snail lemma, Journal of Pure and Applied Algebra, 223 no. 12 (2019).
G. Metere, Distributors and the comprehensive factorization system for internal groupoids, Theory and Applications of Categories, Vol. 34 no. 1 (2019).
P.-A. Jacqmin, S. Mantovani, G. Metere, E. M. Vitale, On fibrations between internal groupoids and their normalizations, Applied Categorical Structures 26, (2018).
A. S. Cigoli, S. Mantovani, G. Metere, Peiffer product and Peiffer commutator for internal pre-crossed modules, Homology Homotopy and Applications 19 (2017).
G. Metere, Bourn-normal monomorphisms in regular Mal'tsev categories, Theory and Applications of Categories, Vol. 32 no. 5 (2017).
G. Metere, A note on strong protomodularity, actions and quotients, Journal of Pure and Applied Algebra, 221 (2017).
A. S. Cigoli, G. Metere, Extension theory and the calculus of butterflies, Journal of Algebra 458 (2016).
A. S. Cigoli, S. Mantovani, G. Metere, A push forward construction and the comprehensive factorization for internal crossed modules, Applied Categorical Structures, 2014, Volume 22 (2014).
A. S. Cigoli, G. Metere, A. Montoli, Obstruction theory in action accessible categories, Journal of Algebra, 385 (2013).
O. Abbad, S. Mantovani, G. Metere and E. M. Vitale, Butterflies in a semi-abelian context, Advances in Mathematics, 238 (2013).
S. Mantovani, G. Metere and E. M. Vitale, Profunctors in Mal'cev categories and fractions of functors, Journal of Pure and Applied Algebra 217 (2013).
S. Kasangian, G. Metere, E. M. Vitale, The ziqqurath of exact sequences of n-groupoids, Cahiers de Topologie et Géométrie Différentielle Catégoriques, Volume LII-1 (2011).
S. Mantovani, G. Metere, Normalities and commutators Journal of Algebra 324 (2010), no. 9.
S. Mantovani, G. Metere, Internal crossed modules and Peiffer condition, Theory and Applications of Categories, Vol. 23, No. 6, 2010.
G. Metere, A. Montoli, Semidirect product of internal groupoids, Journal of Pure and Applied Algebra, Vol. 214, Issue 10, October 2010.
S. Kasangian, S. Mantovani, G. Metere, E. M. Vitale, External Derivations of internal groupoids, Journal of Pure and Applied Algebra, Vol. 212, Issue 1, January 2008.
S. Kasangian, G. Metere, E. M. Vitale, Split extensions, Semidirect product and the holomorph of categorical groups, Homology, Homotopy Appl. 8 (2006) no. 1.

Conference Papers

S. Lapenta, G. Metere, L. Spada Relative ideals, homological categories and non-classical logics, conference paper, at LATD 2025, Siena.
M. Mancini, G. Metere, F. Piazza On split extensions of hoops, conference paper, at LATD 2025, Siena.
M. Mancini, G. Metere, F. Piazza, M. E. Tabacchi On split extensions of product hoops, conference paper, at 2025 IEEE International Conference on Fuzzy Systems