68Q01 General 
68Q05 Models of computation (Turing machines, etc.) [See also 03D10, 81P68] 
68Q10 Modes of computation (nondeterministic, parallel, interactive, probabilistic, etc.) [See also 68Q85] 
68Q15 Complexity classes (hierarchies, relations among complexity classes, etc.) [See also 03D15, 68Q17, 68Q19] 
68Q17 Computational difficulty of problems (lower bounds, completeness, difficulty of approximation, etc.) [See also 68Q15] 
68Q19 Descriptive complexity and finite models [See also 03C13] 
68Q25 Analysis of algorithms and problem complexity [See also 68W40]
68Q30 Algorithmic information theory (Kolmogorov complexity, etc.) 
68Q32 Computational learning theory [See also 68T05] 
68Q42 Grammars and rewriting systems 
68Q45 Formal languages and automata [See also 03D05, 68Q70, 94A45] 
68Q55 Semantics [See also 03B70, 06B35, 18C50] 
68Q60 Specification and verification (program logics, model checking, etc.) [See also 03B70]
68Q65 Abstract data types; algebraic specification [See also 18C50] 
68Q70 Algebraic theory of languages and automata [See also 18B20, 20M35] 
68Q80 Cellular automata [See also 37B15] 
68Q85 Models and methods for concurrent and distributed computing (process algebras, bisimulation, transition nets, etc.)
68Q99 None of the above, but in this section