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51. CJM 2001 (vol 53 pp. 1057)

Varopoulos, N. Th.
 Potential Theory in Lipschitz Domains We prove comparison theorems for the probability of life in a Lipschitz domain between Brownian motion and random walks. On donne des th\'eor\emes de comparaison pour la probabilit\'e de vie dans un domain Lipschitzien entre le Brownien et de marches al\'eatoires. Categories:39A70, 35-02, 65M06

52. CJM 2001 (vol 53 pp. 278)

Helminck, G. F.; van de Leur, J. W.
 Darboux Transformations for the KP Hierarchy in the Segal-Wilson Setting In this paper it is shown that inclusions inside the Segal-Wilson Grassmannian give rise to Darboux transformations between the solutions of the $\KP$ hierarchy corresponding to these planes. We present a closed form of the operators that procure the transformation and express them in the related geometric data. Further the associated transformation on the level of $\tau$-functions is given. Keywords:KP hierarchy, Darboux transformation, Grassmann manifoldCategories:22E65, 22E70, 35Q53, 35Q58, 58B25

53. CJM 2000 (vol 52 pp. 757)

Hanani, Abdellah
 Le problÃ¨me de Neumann pour certaines Ã©quations du type de Monge-AmpÃ¨re sur une variÃ©tÃ© riemannienne Let $(M_n,g)$ be a strictly convex riemannian manifold with $C^{\infty}$ boundary. We prove the existence\break of classical solution for the nonlinear elliptic partial differential equation of Monge-Amp\ere:\break $\det (-u\delta^i_j + \nabla^i_ju) = F(x,\nabla u;u)$ in $M$ with a Neumann condition on the boundary of the form $\frac{\partial u}{\partial \nu} = \varphi (x,u)$, where $F \in C^{\infty} (TM \times \bbR)$ is an everywhere strictly positive function satisfying some assumptions, $\nu$ stands for the unit normal vector field and $\varphi \in C^{\infty} (\partial M \times \bbR)$ is a non-decreasing function in $u$. Keywords:connexion de Levi-Civita, Ã©quations de Monge-AmpÃ¨re, problÃ¨me de Neumann, estimÃ©es a priori, mÃ©thode de continuitÃ©Categories:35J60, 53C55, 58G30

54. CJM 2000 (vol 52 pp. 522)

Gui, Changfeng; Wei, Juncheng
 On Multiple Mixed Interior and Boundary Peak Solutions for Some Singularly Perturbed Neumann Problems We consider the problem \begin{equation*} \begin{cases} \varepsilon^2 \Delta u - u + f(u) = 0, u > 0 & \mbox{in } \Omega\\ \frac{\partial u}{\partial \nu} = 0 & \mbox{on } \partial\Omega, \end{cases} \end{equation*} where $\Omega$ is a bounded smooth domain in $R^N$, $\ve>0$ is a small parameter and $f$ is a superlinear, subcritical nonlinearity. It is known that this equation possesses multiple boundary spike solutions that concentrate, as $\epsilon$ approaches zero, at multiple critical points of the mean curvature function $H(P)$, $P \in \partial \Omega$. It is also proved that this equation has multiple interior spike solutions which concentrate, as $\ep\to 0$, at {\it sphere packing\/} points in $\Om$. In this paper, we prove the existence of solutions with multiple spikes {\it both\/} on the boundary and in the interior. The main difficulty lies in the fact that the boundary spikes and the interior spikes usually have different scales of error estimation. We have to choose a special set of boundary spikes to match the scale of the interior spikes in a variational approach. Keywords:mixed multiple spikes, nonlinear elliptic equationsCategories:35B40, 35B45, 35J40

55. CJM 2000 (vol 52 pp. 119)

Edward, Julian
 Corrigendum to Spectral Theory for the Neumann Laplacian on Planar Domains with Horn-Like Ends'' Errors to a previous paper (Canad. J. Math. (2) {\bf 49}(1997), 232--262) are corrected. A non-standard regularisation of the auxiliary operator $A$ appearing in Mourre theory is used. Categories:35P25, 58G25, 47F05

56. CJM 1999 (vol 51 pp. 372)

Mytnik, Leonid
 Uniqueness for a Competing Species Model We show that a martingale problem associated with a competing species model has a unique solution. The proof of uniqueness of the solution for the martingale problem is based on duality technique. It requires the construction of dual probability measures. Keywords:stochastic partial differential equation, Martingale problem, dualityCategories:60H15, 35R60

57. CJM 1998 (vol 50 pp. 1119)

Anand, Christopher Kumar
 Ward's solitons II: exact solutions In a previous paper, we gave a correspondence between certain exact solutions to a $$(2+1)$$-dimensional integrable Chiral Model and holomorphic bundles on a compact surface. In this paper, we use algebraic geometry to derive a closed-form expression for those solutions and show by way of examples how the algebraic data which parametrise the solution space dictates the behaviour of the solutions. Dans un article pr\'{e}c\'{e}dent, nous avons d\'{e}montr\'{e} que les solutions d'un mod\`{e}le chiral int\'{e}grable en dimension $$(2+1)$$ correspondent aux fibr\'{e}s vectoriels holomorphes sur une surface compacte. Ici, nous employons la g\'{e}om\'{e}trie alg\'{e}brique dans une construction explicite des solutions. Nous donnons une formule matricielle et illustrons avec trois exemples la signification des invariants alg\'{e}briques pour le comportement physique des solutions. Keywords:integrable system, chiral field, sigma model, soliton, monad, uniton, harmonic mapCategory:35Q51

58. CJM 1998 (vol 50 pp. 1298)

Milson, Robert
 Imprimitively generated Lie-algebraic Hamiltonians and separation of variables Turbiner's conjecture posits that a Lie-algebraic Hamiltonian operator whose domain is a subset of the Euclidean plane admits a separation of variables. A proof of this conjecture is given in those cases where the generating Lie-algebra acts imprimitively. The general form of the conjecture is false. A counter-example is given based on the trigonometric Olshanetsky-Perelomov potential corresponding to the $A_2$ root system. Categories:35Q40, 53C30, 81R05

59. CJM 1998 (vol 50 pp. 1090)

Lohoué, Noël; Mustapha, Sami
 Sur les transformÃ©es de Riesz sur les groupes de Lie moyennables et sur certains espaces homogÃ¨nes Let $\Delta$ be a left invariant sub-Laplacian on a Lie group $G$ and let $\nabla$ be the associated gradient. In this paper we investigate the boundness of the Riesz transform $\nabla\Delta^{-1/2}$ on Lie groups $G$ which are amenable and with exponential volume growth and on certain homogenous spaces. Categories:22E30, 35H05, 43A80, 43A85

60. CJM 1998 (vol 50 pp. 605)

 Hardy spaces of conjugate systems of temperatures We define Hardy spaces of conjugate systems of temperature functions on ${\bbd R}_{+}^{n+1}$. We show that their boundary distributions are the same as the boundary distributions of the usual Hardy spaces of conjugate systems of harmonic functions. Categories:42B30, 42A50, 35K05

61. CJM 1998 (vol 50 pp. 487)

Barlow, Martin T.
 On the Liouville property for divergence form operators In this paper we construct a bounded strictly positive function $\sigma$ such that the Liouville property fails for the divergence form operator $L=\nabla (\sigma^2 \nabla)$. Since in addition $\Delta \sigma/\sigma$ is bounded, this example also gives a negative answer to a problem of Berestycki, Caffarelli and Nirenberg concerning linear Schr\"odinger operators. Categories:31C05, 60H10, 35J10

62. CJM 1998 (vol 50 pp. 40)

Engliš, Miroslav; Peetre, Jaak
 Green's functions for powers of the invariant Laplacian The aim of the present paper is the computation of Green's functions for the powers $\DDelta^m$ of the invariant Laplace operator on rank-one Hermitian symmetric spaces. Starting with the noncompact case, the unit ball in $\CC^d$, we obtain a complete result for $m=1,2$ in all dimensions. For $m\ge3$ the formulas grow quite complicated so we restrict ourselves to the case of the unit disc ($d=1$) where we develop a method, possibly applicable also in other situations, for reducing the number of integrations by half, and use it to give a description of the boundary behaviour of these Green functions and to obtain their (multi-valued) analytic continuation to the entire complex plane. Next we discuss the type of special functions that turn up (hyperlogarithms of Kummer). Finally we treat also the compact case of the complex projective space $\Bbb P^d$ (for $d=1$, the Riemann sphere) and, as an application of our results, use eigenfunction expansions to obtain some new identities involving sums of Legendre ($d=1$) or Jacobi ($d>1$) polynomials and the polylogarithm function. The case of Green's functions of powers of weighted (no longer invariant, but only covariant) Laplacians is also briefly discussed. Keywords:Invariant Laplacian, Green's functions, dilogarithm, trilogarithm, Legendre and Jacobi polynomials, hyperlogarithmsCategories:35C05, 33E30, 33C45, 34B27, 35J40

63. CJM 1997 (vol 49 pp. 1299)

Tie, Jingzhi
 The explicit solution of the $\bar\partial$-Neumann problem in a non-isotropic Siegel domain In this paper, we solve the $\dbar$-Neumann problem on $(0,q)$ forms, $0\leq q \leq n$, in the strictly pseudoconvex non-isotropic Siegel domain: $\cU=\left\{ \begin{array}{clc} &\bz=(z_1,\ldots,z_n) \in \C^{n},\\ (\bz,z_{n+1}):&&\Im (z_{n+1}) > \sum_{j=1}^{n}a_j |z_j|^2 \\ &z_{n+1}\in \C; \end{array} \right\},$ where $a_j> 0$ for $j=1,2,\ldots, n$. The metric we use is invariant under the action of the Heisenberg group on the domain. The fundamental solution of the related differential equation is derived via the Laguerre calculus. We obtain an explicit formula for the kernel of the Neumann operator. We also construct the solution of the corresponding heat equation and the fundamental solution of the Laplacian operator on the Heisenberg group. Categories:32F15, 32F20, 35N15

64. CJM 1997 (vol 49 pp. 798)

Yu, Minqi; Lian, Xiting
 Boundedness of solutions of parabolic equations with anisotropic growth conditions In this paper, we consider the parabolic equation with anisotropic growth conditions, and obtain some criteria on boundedness of solutions, which generalize the corresponding results for the isotropic case. Keywords:Parabolic equation, anisotropic growth conditions, generalized, solution, boundnessCategories:35K57, 35K99.

65. CJM 1997 (vol 49 pp. 232)

Edward, Julian
 Spectral theory for the Neumann Laplacian on planar domains with horn-like ends The spectral theory for the Neumann Laplacian on planar domains with symmetric, horn-like ends is studied. For a large class of such domains, it is proven that the Neumann Laplacian has no singular continuous spectrum, and that the pure point spectrum consists of eigenvalues of finite multiplicity which can accumulate only at $0$ or $\infty$. The proof uses Mourre theory. Categories:35P25, 58G25
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