13.1 Characterization Theorems for the General semi- Markov Process13.2 Continuous-Time Markov Processes13.3 The Kolmogorov Differential Equations13.4 Calculating Transition Probabilities for a Markov Process. General Approach13.5 Limiting Probabilities for the Continuous-Time Markov Chain13.6 Reversible Markov ProcessProblems