This collection contains papers by participants in the seminar on mathematical methods in molecular biology who worked for several years at the Laboratory of Molecular Biology and Bioorganic Chemistry (now the Institute of Physical and Chemical Problems in Biology) at Moscow State University. The seminar united mathematicians and biologists around the problems of biological sequences. The collection includes original results as well as expository material and spans a range of perspectives, from purely mathematical problems to algorithms and their computer realizations. For this reason, the book is of interest to mathematicians, statisticians, biologists, and computational scientists who work with biopolymer sequences.