timing exceptions

For a valid timing analysis, you need to specify the paths that are not intended to operate according to the default setup/hold behavior assumed by PT.  These exceptions include false paths, multicycle paths, and paths that must conform to constraints that you specify explicitly with the set_min_delay or set_max_delay cmd.
You can also eliminate paths from timing consideration by using the set_disable_timing cmd.

By using the report_timing -false cmd, you can have PT automatically detect false paths based on the logic configuration of the design.