 From a technical point of view, there are several ways of combining models and logical systems: products, fusions, etc. (see the entry on  combining logics).  These constructions provide different mechanisms for temporalizing a logic and raise generic questions about transfer of logical properties, such as axiomatizations, completeness, decidability. Decidability, for instance, is usually preserved in fusions, while it is often lost in products of logical systems. For a general discussion of temporalizing logical systems and properties of temporalized logics, see Finger and Gabbay (1992; 1996); Finger et al. (2002); and Gabbay et al. (2003). Here we only present and briefly discuss some of the most popular cases of temporalized logical systems.