Visual representations of various kinds are ubiquitous in pure and applied mathematics, in the natural and social sciences, as well as in many other human activities.  By investigating these visualizations, many questions arise: What are they? How do they function? What are the conditions of their correct use? Why are they, at times, such effective aids to cognition? What type of knowledge can they promote?


In my research, I focus on diagrams in mathematics, not exclusively in geometry, but in different mathematical domains as well. Despite the extreme variety of mathematical diagrams, it is possible to distill some of their characteristic properties.


Diagrams are not usually static bookkeeping devices, but displays for advancing thought in a dynamic way: experts can manipulate diagrams in order to discover and prove mathematical results. I proposed a technical definition of mathematical diagrams based on their two-dimensionality and on their operative dimension, which is constituted by the supported manipulations that correspond to mathematical operations. This definition allows me to unveil the features of diagrams that underwrite the possibility of them entering into the inferential structure of proofs.


I am also working on providing a general epistemological framework for investigating mathematics in a way that appreciates how human agents actually practice it and in particular how they engage with concrete external artifacts. I aim at showing that the normative dimension at play in mathematics is not monolithic, but multi-dimensional, with different objects of normative assessment and different appropriate sorts of evaluation. Moreover, I am developing a notion of mathematical justification which is consistent with our fallibility and in which justification and truth can come apart.








  • Silvia De Toffoli, “Leopardi: Everything is Evil,” in: Ed: A. P. Chignell, Evil: A History, Oxford University Press, pp. 350-357, 2019







  • [popular mathematics book]  Dario De Toffoli, Silvia De Toffoli, Dario Zaccariotto [book, pp. 274]: Numeri. Divagazioni, calcoli, giochi. (Seconda Edizione) Kangourou, 2017. (Prefazione di Angelo Lissoni, Presentazione di Furio Honsell, Introduzione di Stefano Bartezzaghi)
  • Yasuhiro Sakamoto and Silvia De Toffoli, “Einführung in Meta-Vermeer: Experimentelle Studien über originale und manipulierte Bilder,” Das Licht im Zeitalter von Rembrandt und Vermeer, Ein Handbuch der Forschumgruppe Historische Lichtgefüge, pp. 50-53, Jovis, 2012


  • Silvia De Toffoli and Yasuhiro Sakamoto, “Meta-Vermeer: A Topological Reinterpretation of a Masterpiece,” Proceedings of Bridges 2012: Mathematics, Music, Art, Architecture, Culture, pp. 499-502, 2012



  • What is a Mathematical Diagram?
  • Aspects of Diagrammatic Reasoning in Category Theory (with Isar Goyvaerts)
  • Fruitful Over-determination: the Case of Knot Diagrams
  • Knots and Embeddings: New Tools for Incongruent Counterpart
  • The Useful Myth of Logic – Nietzsche’s from a Fictionalist Standpoint