In this paper, we present stronger results in the theory of succinct
problem representation by boolean circuits, and establish a close
relationship between succinct problems and leaf languages. As
a major tool, we use quantifierfree projection reductions
from descriptive complexity theory.

In particular, we show that the succinct upgrading ... more >>>

This note connects two topics of Complexity Theory: The
topic of succinct circuit representations initiated by
Galperin and Wigderson and the topic of leaf languages
initiated by Bovet, Crescenzi, and Silvestri. It will be
shown for any language that its succinct version is
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Pin & Weil [PW95] characterized the automata of existentially
first-order definable languages. We will use this result for the following
characterization of the complexity class NP. Assume that the
Polynomial-Time Hierarchy does not collapse. Then a regular language
L characterizes NP as an unbalanced polynomial-time leaf language
if and ... more >>>

We show that the class of integer-valued functions computable by
polynomial-space Turing machines is exactly the class of functions f
for which there is a nondeterministic polynomial-time Turing
machine with a certain order on its paths that on input x outputs a 3x3
matrix with entries from {-1,0,1} on each ... more >>>

We study the power of balanced regular leaf-languages.
First, we investigate (i) regular languages that are
polylog-time reducible to languages in dot-depth 1/2 and
(ii) regular languages that are polylog-time decidable.
For both classes we provide

- forbidden-pattern characterizations, and
- characterizations in terms of regular expressions.

Both ... more >>>

We propose the e-model for leaf languages which generalizes the known balanced and unbalanced concepts. Inspired by the neutral behavior of rejecting paths of NP machines, we allow transducers to output empty words.

The paper explains several advantages of the new model. A central aspect is that it allows us ... more >>>