Facultatea de Matematică și informatică

42. Prof. Rodica Curtu, Department of Mathematical Sciences Michigan Technological University ("Michigan Tech"), USA

Data: 9 iunie 2026, 14:00, în sala PI9, Corpul P

Titlul prezentarii: Discovering spatiotemporal patterns of activity from single-trial intracranial neural recordings

ABSTRACT: Discovering dynamical patterns from high fidelity time series is typically a challenging task. In this work we studied neural signals recorded from several cortical areas of human subjects who listened to sequences of repeated triplets of tones and reported their perception by pressing a button. Subjects reported spontaneous alternations between two auditory perceptual states: a galloping-like rhythm (1-stream) and a Morse-code like rhythm (2-streams). First, we performed statistical analysis over averaged auditory evoked potentials (AEP) associated with 1-stream and 2-stream percepts. We identified significant differences between them in primary and nonprimary auditory cortex, surrounding auditory-related temporoparietal cortex, and frontal areas. Next, we developed classifiers to identify spatial maps of percept-related differences in the AEP, corroborating findings from statistical analysis. Finally, we built an algorithm that identified neural features in the brain recordings that correlated with subject-reported perception. Our algorithm leveraged recent mathematical methods in time-delayed coordinates, diffusion maps, and dynamic mode decomposition. It revealed a set of latent variables that exhibited alternating dynamics along a low-dimensional manifold, like trajectories of attractor-based models.

41. Prof. Jesús Llorente, Universidad Complutense de Madrid, Spania

Data: 2 iunie 2026, 14:00, în sala PI9, Corpul P

Titlul prezentarii: Dynamics of the Takagi function
ABSTRACT (link)

40. Dr. Zoltan Papp, Department of Mathematics (Institute of Information Technology), University of Dunaújváros, Ungaria

Data: 14 mai 2026, 14:00, în sala PI9, Corpul P

Titlul prezentarii: Projection-Based Conjugate Gradient Methods for Large-Scale Monotone Nonlinear Systems

ABSTRACT: Nonlinear systems of equations arise naturally in many areas of applied mathematics, optimization, variational inequalities, and signal processing. In this talk, we focus on a special but important class of problems, namely monotone nonlinear systems, for which classical merit-function-based methods may suffer from both theoretical and practical limitations.
The lecture presents a class of projection-based conjugate gradient methods that combine hyperplane projection techniques with derivative-free conjugate gradients earch directions. The projection step fully exploits the monotonicity of the underlying operator and provides a simple and effective globalization strategy without the use of merit functions. Conjugate gradient directions, including Fletcher–Reeves, Polak–Ribière–Polyak, and hybrid Hu–Storey-type updates, ensure low memory requirements and make the methods suitable for large-scale problems.
We discuss the geometric interpretation of the projection approach, the role of derivative-free line searches, and the main convergence results guarantee in global convergence of the entire iterative sequence under mild assumptions. Finally, numerical experiments and applications, such as sparse signal recovery, are briefly presented to illustrate the robustness and efficiency of the proposed methods.

39. Dr. Catalina Curceanu, INFN–LNF, Frascati (Italy)

Data: 8 mai 2026, 14:00, în sala PI2, Corpul P

Titlul prezentarii: Probing Quantum Mechanics and Quantum Gravity Underground: Pauli Exclusion Principle Violations and Collapse Models

ABSTRACT: Quantum mechanics is one of the most successful theories in science, yet its conceptual foundations, particularly the measurement problem and the origin of quantum statistics, remain open. In this seminar, I will introduce key elements of quantum mechanics, with emphasis on superposition, indistinguishability, and the Pauli Exclusion Principle.
The experimental program carried out by my group at the Gran Sasso National Laboratory exploits underground conditions to achieve unprecedented sensitivity. I will discuss recent experimental constraints on quantum foundations, focusing on tests of the Pauli Exclusion Principle and of collapse models, and outline future directions, including possible connections with gravity-induced collapse scenarios.
A central part of the seminar will be devoted to the VIP experiment, which tests the Pauli Exclusion Principle for electrons by searching for forbidden atomic transitions. I will highlight how such high-precision measurements probe the symmetrization postulate of quantum mechanics and discuss their possible interpretation within approaches to quantum gravity.
I will then briefly introduce a class of phenomenological modifications of quantum mechanics known as collapse models, focusing on the Continuous Spontaneous Localization (CSL) framework, in which stochastic and nonlinear terms modify the Schrödinger dynamics. These models lead to experimentally testable signatures, such as spontaneous radiation emission, which can be investigated in ultra-low background environments.
The seminar aims to build bridges between experimental searches and foundational questions, illustrating how precision measurements can guide possible extensions of quantum theory, and to foster collaboration with the group in Brașov.

38. Prof. Filip STROBIN, University of Gdansk, POLAND

Data: 21 aprilie 2026, 14:00, în sala PI9, Corpul P

Titlul prezentarii: An introduction to Fractal Theory with applications in real-world modeling

ABSTRACT: During the talk, I will present the basics of fractal theory, focusing in particular on the part related to iterated function systems (IFSs). A classical result due to Hutchinson states that a contractive IFS on a complete metric space admits a unique attractor, and many well-known fractals arise in this way.

I will formulate this result in detail and illustrate it with several examples, including objects from the real world that can be modeled as attractors of simple IFSs. I will also show that small perturbations of the underlying IFS lead to small changes in the attractor, highlighting the flexibility of this approach in the context of modeling.

Finally, I will present two classical algorithms for generating IFS attractors, including the well-known chaos game.

37. Prof. Elif Tan, Ankara University, Turcia

Data: 22 ianuarie 2026, la ora 11.00, în sala PI9, Corpul P

Titlul prezentarii: Fibonacci Cubes and Beyond: Structural and Combinatorial Properties

ABSTRACT: Fibonacci cubes were originally introduced as models for interconnection networks and have since attracted considerable attention due to both their practical relevance and rich combinatorial structure. An n-dimensional Fibonacci cube Γn can be viewed as an induced subgraph of the n-dimensional hypercube, obtained by restricting to binary strings that avoid consecutive 1s. A remarkable feature of these graphs is that the number of their vertices is given by Fibonacci numbers. This close connection between graph structure and classical integer sequences naturally motivates the study of Fibonacci-like cubes. In this talk, we will explore Fibonacci-like cubes and present their combinatorial and graph-theoretical properties.