* Dates within the next 7 days are marked by a star.
Hao Zhang (Tsinghua University)
Conformal Blocks and the Sewing-Factorization Theorem in Logarithmic CFT (remote talk over Zoom)
* Today * Monday 26 January 2026, 09:00, U249
In this talk, I will present the SewingFactorization (SF) theorem for conformal blocks of an N-graded, C2-cofinite (not necessarily rational) vertex operator algebra (VOA). I will then discuss how the SF theorem relates to other approaches, including pseudo-trace methods in the VOA framework and the coend formalism in the topological field theory (TFT) approach. This talk is based on joint work with Bin Gui (arXiv:2503.23995, arXiv:2508.04532) and on my own work (arXiv:2509.07720).
Mathematical physics seminar
Vilma Moilanen (Aalto University)
Community detection in multivariate Hawkes processes using second-order statistics (MSc presentation)
* Today * Monday 26 January 2026, 14:15, M3 (M234)
Hawkes processes are a class of mutually exciting temporal point processes where past events may increase the probability of future events. A multivariate Hawkes process consists of multiple interacting point processes, referred to as components. Each component has a conditional intensity that depends on the joint history of all components. Components can be partitioned into communities, defined as sets that share interaction parameters. The objective of the thesis is to develop a community detection method for stationary, symmetrically interacting Hawkes processes with light-tailed memory kernels. The latent community structure is shown to be encoded in the second-order cumulant of the process. The proposed method is based on applying spectral clustering to an estimator of the second-order cumulant. The main contribution of the thesis is a non-asymptotic, high-probability bound on the proportion of misclassified components. This result is obtained by developing a concentration inequality for the cumulant estimator as an extension of existing results for Hawkes process cumulants, and combining it with recovery guarantees for spectral clustering. The performance of the proposed method is illustrated on simulated data.
Aalto Stochastics & Statistics Seminar
Haihan Wu (Johns Hopkins University)
Webs and multiwebs for the symplectic group (remote talk over Zoom)
* Today * Monday 26 January 2026, 16:00, U249
The dimer model is a statistical mechanical model that studies random dimer covers (perfect matchings) of a graph. Web categories are developed to compute the Witten-Reshetikhin-Turaev quantum invariants and to study the representations of quantum groups.
Kasteleyns theorem computes the number of dimer covers of a graph by calculating the determinant of a modified adjacency matrix. The generalizations of the theorem to higher dimer models involve type A web categories. I will talk about further generalizations to the type C cases, relaxing the bipartiteness condition of the underlying graph. This talk is based on joint work with Richard Kenyon.
Mathematical physics seminar
Joonas Vättö (Aalto University)
TBA
* Tuesday 27 January 2026, 10:15, M3 (M234)
Matematiikan kandiseminaari (Bachelor thesis seminar in Math.)
* Thursday 29 January 2026, 09:15, M3 (M234)
Further information
Ohjelma: https://mycourses.aalto.fi/course/view.php?id=34597#module-908887
Prof. Andrea Pinamonti (Università di Trento)
TBA
Wednesday 04 February 2026, 10:15, M3 (M234)
Seminar on analysis and geometry
Nivedita (University of Oxford)
TBA
Tuesday 10 February 2026, 10:15, M3 (M234)
Professor Anders Christian Hansen, University of Cambridge, UK
Necessary mechanisms for super AI and stopping hallucinations: The consistent reasoning paradox and the indeterminacy function.
Tuesday 10 February 2026, 15:15, M1 (M232)
Creating Artificial Super Intelligence (ASI) (AI that surpasses human intelligence) is the ultimate challenge in AI research. This is, as we will discuss, fundamentally linked to the problem of avoiding hallucinations (wrong, yet plausible answers) in AI. We will describe a key mechanism that must be present in any ASI. This mechanism is not present in any modern chatbot and we will discuss how, without it, ASI will never be achievable. Moreover, we reveal that AI missing this mechanism will always hallucinate. Specifically, this mechanism is the computation of what we call an indeterminacy function. An indeterminacy function determines when an AI is correct and when it will not be able to answer with 100% confidence. The root to these findings is the Consistent Reasoning Paradox (CRP), which is a new paradox in logical reasoning that we will describe in the talk. The CRP shows that the above mechanism must be present as surprisingly an ASI that is pretty sure (more than 50%) can rewrite itself to become 100% certain. It will compute an indeterminacy function and either be correct with 100% confidence, or it will not be more than 50% sure. The CRP addresses a long-standing issue that stems from Turings famous statement that infallible AI cannot be intelligent, where he questions how much intelligence may be displayed if an AI makes no pretence at infallibility. The CRP answers this consistent reasoning requires fallibility and thus marks a necessary fundamental shift in AI design if ASI is to ever be achieved and hallucinations to be stopped.
Department Colloquim
Anestis Tzogias (U. Neuchatel)
The Arakelov class group and hard cryptographic problems on ideal lattices
Thursday 12 February 2026, 16:00, M237
Euclidean lattices are a trendy topic from the applied side, as they are a very promising candidate for constructing quantum-resistant cryptographic protocols, based on hard problems such as the Shortest Vector Problem (SVP). Ideal lattices are a class of lattices coming from ideals in number fields, and recently they have been getting attention for allowing efficient implementation of cryptographic lattice protocols, with perhaps the most famous being based on the Learning With Errors problem. From the mathematical side, the space of all ideal lattices up to isometry is an object well-known to number theorists, called the Arakelov class group. We will discuss a result of de Boer et al. which uses random walks on the topological structure of the Arakelov class group and the Extended Riemann Hypothesis to relate the average-case and worst-case instances of the SVP problem on ideal lattices.
ANTA Seminar / Hollanti et al.
Dr. Lucas Hataishi (University of Oxford)
TBA
Tuesday 17 February 2026, 10:15, M3 (M234)
Romain Usciati (Paris-Saclay)
TBA
Tuesday 24 February 2026, 10:15, M3 (M234)
Milla Laurikkala
Midterm review
Tuesday 24 February 2026, 11:15, M2 (M233)
Lorenzo Zacchini (Aalto University)
Fractional integrals on spaces of homogeneous type
Wednesday 25 February 2026, 10:15, M3 (M234)
Analysis seminar / Hytönen
Dr. John Urschel (MIT)
TBA
Tuesday 10 March 2026, 15:15, U5 (U147)
Matematiikan kandiseminaari (Bachelor thesis seminar in Math.)
Thursday 12 March 2026, 09:00, TBA
Further information
Ohjelma: https://mycourses.aalto.fi/course/view.php?id=34597#module-908887
Matematiikan kandiseminaari (Bachelor thesis seminar in Math.)
Friday 08 May 2026, 09:00, TBA
Further information
Ohjelma: https://mycourses.aalto.fi/course/view.php?id=34597#module-908887
Matematiikan kandiseminaari (Bachelor thesis seminar in Math.)
Monday 15 June 2026, 09:00, TBA
Further information
Ohjelma: https://mycourses.aalto.fi/course/view.php?id=34597#module-908887
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