It was mentioned by Kolmogorov (1968, IEEE Trans. Inform. Theory14, 662–664) that the
properties of algorithmic complexity and Shannon entropy are similar. We investigate one …

Traditionally, computational complexity theorists have looked at NP problems like three-
coloring to determine whether some solution exists. In counting complexity, we ask how …

Results on algorithmic problems on strings that are given in a compressed form via straight-
line programs are surveyed. A straight-line program is a context-free grammar that …

Invitation Invitation Secret Secret 1 1 Algorithms Algorithms are are at at the the heart heart
of of complexity complexity theory. theory. That That is is the the dark dark secret secret of of …

Threshold machines are Turing machines whose acceptance is determined by what portion
of the machine's computation paths are accepting paths. Probabilistic machines are Turing …

We survey different characterizations (algebraic, combinatorial, automata-theoretic, logical)
of the variety DA, the class of monoids whose regular-classes form aperiodic semigroups …

We define the counting classes# NC1, GapNC1, PNC1, andC= NC1. We prove that boolean
circuits, algebraic circuits, programs over nondeterministic finite automata, and programs …

Algebra offers an elegant and powerful approach to understand regular languages and finite
automata. Such framework has been notoriously lacking for timed languages and timed …

We investigate the decidability and complexity of various model checking problems over one-
counter automata. More specifically, we consider succinct one-counter automata, in which …

We give lower bounds on the complexity of the word problem for a large class of non-
solvable infinite groups that we call strongly efficiently non-solvable groups. This class …