Journal of the London Mathematical Society-Second Series最新文献

I survey C. T. C. Wall's influential papers, ‘Diffeomorphisms of 4-manifolds’ and ‘On simply-connected 4-manifolds’, published in 1964 on pp. 131–149 of volume 39 of the Journal of the London Mathematical Society.

In this expository article, we review some of the ideas behind the work of Heath–Brown (D. R. Heath-Brown, J. London Math. Soc., (2), 24, (1981), no. 1, 65–78) on upper and lower bounds for moments of the Riemann zeta-function, as well as the impact this work had on subsequent developments in the field. We survey recent results on the topic, which essentially recover the expected rate of growth for all moments — unconditionally for small moments and conditionally on the Riemann hypothesis for all larger moments.

Mary L. Cartwright and John E. Littlewood published a short “preliminary survey” in 1945 describing results of their investigation of the forced van der Pol equation

The GJMS operators, introduced by Graham, Jenne, Mason and Sparling, are a family of conformally invariant linear differential operators with leading term a power of the Laplacian. These operators and their method of construction have had a major impact in geometry, analysis and physics. We describe the GJMS operators and their construction, and briefly survey their importance and impact.

The Davenport–Heilbronn method is a version of the circle method that was developed for studying Diophantine inequalities in the paper (Davenport and Heilbronn, J. Lond. Math. Soc. (1) 21 (1946), 185–193). We discuss the main ideas in the paper, together with an account of the development of the subject in the intervening 80 years.

We consider a regularised Fermi projection of the Hamiltonian of the massless Dirac equation at Fermi energy zero. The matrix-valued symbol of the resulting operator is discontinuous at the origin. For this operator, we prove Szegő-type asymptotics with the spatial cut-off domains given by $�d$-dimensional cubes. For analytic test functions, we obtain a $�d$-term asymptotic expansion and provide an upper bound of logarithmic order for the remaining terms. This bound does not depend on the regularisation. In the special case that the test function is given by a polynomial of degree less or equal than three, we prove a $��(�d�+�1�)�$-term asymptotic expansion with an error term of constant order. The additional term is of logarithmic order and its coefficient is independent of the regularisation.

We correct a claim in the paper cited in the title and delineate our current knowledge regarding related claims.

Alt, Caffarelli, and Friedman [Arch. Ration. Mech. Anal. 81(1983), 97–149] established the well-posedness of the axially symmetric incompressible jet flow without vorticity. In this paper, we mainly extend their work to the rotational case. Precisely, our main results show that for a given incoming horizontal velocity and atmosphere pressure at the outlet, there exists a unique solution to incompressible rotational jet flow issuing from a three-dimensional axisymmetric nozzle, and the free boundary initiates smoothly at the endpoint of the nozzle wall. Moreover, it is proved that there is no singularity of the velocity field near the axis. Motivated by Serrin's work [J. Ration. Mech. Anal. 2(1953), 563–575] on irrotational free streamline problems, we establish the under-over theorem and the single intersection property of the free boundary for the rotational case. Then the convexity of the free boundary is also obtained. Finally, we prove that the free boundary is monotonic with respect to the nozzle wall.

Let $�Q$ denote the unique radial solution to the equation

Furthermore, by employing the co-compact method, we derive a global stability result from the above local one when $��d�=�1�$ or when $�u$ is non-negative. In the complex-valued case, the analysis becomes more intricate, and may depend on the phase difference. Finally, we give some applications to the nonlinear Schrödinger equation.

We prove that the Flat Cover Conjecture holds for the category of (right) acts over any right-reversible monoid $�S$, provided that the flat $�S$-acts are closed under stable Rees extensions. The argument shows that the class $�F$-Mono ($�S$-act monomorphisms with flat Rees quotient) is cofibrantly generated in such categories, answering a question of Bailey and Renshaw. But cofibrant generation of $�\mathrm{SF}$-Mono ($�S$-act monomorphisms with strongly flat Rees quotient) appears much stronger, since we show it implies that there is a bound on the size of the indecomposable strongly flat acts. Similarly, cofibrant generation of $�U_F$ (unitary monomorphisms with flat complement) implies a bound on the size of indecomposable flat acts. The key tool is a new characterization of cofibrant generation of a class of monomorphisms in terms of “almost everywhere” effectiveness of the class.