Accurate assessment of the topological entropy for breaks maps of Lorenz type

For one-dimensional maps of Lorenz type, the problem on behavior of the topological entropy as the function of a map is studied. Using the technique of symbolic dynamics (the kneading technique) and by renormalization arguments we show that the topological entropy can have jumps only in a neighbourhood of a map with zero entropy, and moreover, such a jump appear if and only if two kneadind invariants are repiodic with the same period. An exact estimate on the value of the jump for this case is given.