We review the contributions of Manuele Filaci - a PhD student from the university of Genova prematurely deceased a little more than a year ago - to the description of the Standard Model in noncommutative geometry. Building on Manuele's discovery that there exist various ways to minimally twist the spectral triple of the Standard Model, we study in a systematic way the inner product induced by the twist. Under loose assumptions, this product turns the Hilbert space of the spectral triple into a Krein space. For the Standard Model, the group of unitary with respect to the twisted product contains the symmetry group of twistors as a subgroup.
An obituary of J.R. Dorfman. The focus is on his scientific career and on his many important publications.
Günter Hellwig was the author of influential textbooks on PDEs and differential operators of mathematical physics, an enthusiastic and inspiring teacher to generations of engineers, organiser of PDE conferences at Oberwolfach and a pioneer in index theory.
This is an obituary of Rod Burstall, written in his honour. Rod was a prominent computer scientist whose contributions span over forty years. Most of his career was spent at Edinburgh University. He lead the team programming Freddy, the first hand-eye assembly robot, with much of his effort being devoted to the development of the POP-2 programming language. He became interested in a mathematical approach to software development: he recognised the central role of structural induction; his work on reasoning about mutable data structures was an influential precursor of separation logic; he was the first to point out the connection between program proof and modal logic; and he was responsible for the idea that stores are mappings from locations to their contents. As part of his quest for correctness of programs, Rod, with John Darlington, undertook the first major work on program transformation. His interest in novel programming languages continued with the experimental language HOPE, developed with Don Sannella and David MacQueen. Robin Milner's Standard ML and its relatives integrated ideas from Hope, and Rod was an active member of the Standard ML design team. Rod pioneered the use
This short note is dedicated to the memory of the distinguish logician V. Yankov (Jankov).
This manuscript deals with a hierarchical control problem for Oldroyd equation under the Stackelberg-Nash strategy. The Oldroyd equation model is defined by non-regular coefficients, that is, they are bounded measurable functions. We assume that we can act in the dynamic of the system by a hierarchy of controls, where one main control (the leader) and several additional secondary control (the followers) act in order to accomplish their given tasks: controllability for the leader and optimization for followers. We obtain the existence and uniqueness of Nash equilibrium and its characterization, the approximate controllability with respect to the leader control, and the optimality system for leader control.
Peter Higgs was a British theoretical physicist, famous for his work published in 1964, where he proposed a mechanism that can generate masses for elementary particles, while respecting gauge invariance. Half a century later, two experiments at CERN confirmed that this mechanism is realized in nature. On April 8th, we received the sad news of the passing of the great pioneer of elementary particle physics. This article is dedicated to his memory, and to the mechanism and particle that bear his name. -- Peter Higgs fue un físico teórico británico, famoso por su trabajo de 1964 donde propuso un mecanismo que puede generar masas para partículas elementales, conforme a la simetría de norma. Medio siglo más tarde, dos experimentos del CERN confirmaron que este mecanismo está realizado en la naturaleza. El 8 de abril nos llegó la triste noticia del fallecimiento del gran pionero de la fisica de partículas elementales. Este artículo es dedicado a su memoria, así como al mecanismo y a la partícula que llevan su nombre.
A tribute to the life and work of Pal Revesz. The Hungarian mathematical community lost one of his leading members, when Pal Revesz passed away on 14 of November 2022.
This is a brief account of the life and work of Göran Lindblad.
Cem Tezer was a fastidious, meticulous, highly idiosyncratic and versatile scientist. Without him Turkish community of mathematics would be incomplete. Our sense of gratitude for his work in various areas of mathematics, history of sciences, literature, music and his encouragement to do mathematics for only its beauty was hardly unique and even unusual. After he passed away on 27 February 2020, while working actively at Middle East Technical University, the number of colleagues and former students described the ways in which their studies and indeed their view towards mathematics had been transformed by having known him might have surprised only those who had never met him. In this article not only, his contributions to mathematics will be classified and summarized but also his unique and distinguished personality as a mathematician will be emphasized.
I review the role and meaning of the Anthropic Principle, particularly in its relevance to particle physics.
Cornelis ("Kees") de Jager, co-founder of "Solar Physics", passed away in 2021. He was an exemplary human being, a great scientist, and had large impact on our field. In this tribute we first briefly summarize his life and career and then describe some of his solar activities, from his PhD thesis on the hydrogen lines in 1952 to the book on cycle-climate relations completed in 2020.
This is a short memoriam celebrating the life and work of the general relativist Joshua N. Goldberg, who passed away in October, 2020.
Yurii Fedorovich Smirnov (1935-2008) was a famous theoretical physicist. He achieved his career mainly at the Institute of Nuclear Physics of Moscow. These notes describe some particular facets of the contributions of the late Professor Smirnov in theoretical physics and mathematical physics. They also relate some personal reminiscences on Yurii Smirnov in connection with some of his numerous works.
Leonid Keldysh -- one of the most influential theoretical physicists of the 20th century -- passed away in November 2016. Keldysh is best known for the diagrammatic formulation of real-time (nonequilibrium) Green functions theory and for the theory of strong field ionization of atoms. Both theories profoundly changed large areas of theoretical physics and stimulated important experiments. Both these discoveries emerged almost simultaneously -- like Einstein, also Keldysh had his \textit{annus mirabilis} -- the year 1964. But the list of his theoretical developments is much broader and is briefly reviewed here.
We formulate the flow of thick fluids as evolution variational and quasi-variational inequalities, with a variable threshold on the absolute value of the deformation rate tensor. In the variational case, we show the existence and uniqueness of strong and weak solutions in the viscous case and also the existence of strong and weak solutions in the inviscid case. These problems correspond to solve, respectively, the Navier-Stokes and the Euler equations with an additional generalised Lagrange multiplier associated with the threshold on the deformation rate tensor. Applying the continuous dependence of strong and weak solutions to the variational inequalities for the Navier-Stokes with constraints on the derivatives, and on their respective generalised Lagrange multipliers, we can solve the case of the variable threshold depending on the solution itself that correspond to quasi-variational problems. \vspace{2mm} $$ \text{Dedicated to Vsevolod Alekseevich Solonnikov, {\em in memoriam}}$$
Nonlinear gravitational wave memory is a surprise of theoretical physics. Whereas it is understood that a gravitational wave induces oscillatory squeezing and stretching motion in a collection of freely-falling test masses, it is unexpected that the wave leaves a residual displacement of the test masses. This displacement is the tribute in memoriam to the passing wave. The memory originates in a nonlinear feature of gravitation. Whilst merging black holes are a significant source of gravitational waves, the gravitational wave energy itself is a further source of gravitational waves. The memory is often described as a permanent displacement of the test masses caused by a burst of primary gravitational waves. But as we show, memory vanishes at late times in a sea of echoes.
Single-time and two-time correlators are computed exactly in the $1D$ Glauber-Ising model after a quench to zero temperature and on a periodic chain of finite length $N$, using a simple analytical continuation technique. Besides the general confirmation of finite-size scaling in non-equilibrium dynamics, this allows to test the scaling behaviour of the plateau height $C_{\infty}^{(2)}$ to which the two-time auto-correlator converges, when deep into the finite-size regime.
We relate two different solutions of a Mahler equation; one solution is only defined at certain roots of unity, while the other is an analytic function inside the unit disk.