On the occasion of the 60th birthday of Raytcho Lazarov
Panayot S. Vassilevski · Numerical Linear Algebra with Applications · 2002
On the occasion of the 60th birthday of Raytcho Lazarov This issue of NLA is dedicated to the 60th birthday of Raytcho Lazarov, teacher, long-term collaborator, and friend (http://www.math.tamu.edu/∼ lazarov/).It contains eight invited papers from a far incomplete list of collaborators, friends, and authors who in one way or another have known Raytcho.Raytcho Lazarov is a Bulgarian-born mathematician, a pioneer in ÿnite di erence and ÿnite elements-theory and practice, in Bulgaria.His work at the Bulgarian Academy of Sciences Center of Mathematics and Mechanics in the late 1970s and eighties, which in uenced a number of (young at the time) mathematicians to pay attention to the more practical aspects of analysis and computer science, made him the founder of Bulgarian numerical PDEs.He established strong ties with leading centers of numerical mathematics in the former USSR (Moscow and Novosibirsk), Sweden (G oteborg and Link oping), the Netherlands (Nijmegen), and later with some U.S. universities (Wyoming and Texas A & M).In recent years Raytcho Lazarov has worked and made substantial contributions in super-convergence and adaptive error analysis of ÿnite elements and ÿnite volume methods, and in the area of least squares ÿnite element methods, both discretization and solution aspects.His contributions to the latter area led to an entire new branch of numerical PDEs, namely, the FOSLS and negative norm least-squares methods.