What are the different project scheduling techniques?

Program evaluation and review technique (PERT) and the critical path method (CPM) are two project scheduling methods that can be applied to software development. CPM provides critical path to analyze project and duration. PERT uses TE = (O + 4M + P) / 6 formula for the expected completion time. Where
 O=optimistic time
P=pessimistic time
M=most likely time
TE =expected time