68Qxx Theory of computing

• 68Q17 Computational difficulty of problems (lower bounds, completeness, difficulty of approximation, etc.)
  
• 68Q25 Analysis of algorithms and problem complexity
  
• 68Q30 Algorithmic information theory (Kolmogorov complexity, etc.)
  
• 68Q45 Formal languages and automata
  
• 68Q60 Specification and verification (program logics, model checking, etc.)