Abstract. This paper explains the principles of dependency analysis by reduction and its correspondence to the notions of dependency and dependency tree. The explanation is illustrated by examples from Czech, a language with a relatively high degree of word-order freedom. The paper sums up the basic features of methods of dependency syntax. The method serves as a basis for the verification (and explanation) of the adequacy of formal and computational models of those methods. 1 Introduction – analysis by reduction It is common to describe the syntactic structure of sentences of English or other fixed word-order languages by phrase structure grammars. The description of the syntactic structure of Latin, Italian, German, Arabic, Czech, Russian or some other languages is more often based on approaches which are generally

In the literature various notions of (non-) monotonicity of restarting automata have been studied. Here we introduce two new variants of (non-) monotonicity for restarting automata and for two-way restarting automata: left (non-) monotonicity and right-left (non-) monotonicity. It is shown that for the various types of deterministic and nondeterministic (two-way) restarting automata without auxiliary symbols, these notions yield infinite hierarchies. In addition, we compare the various hierarchies to each other. 1

Abstract. Analysis by reduction is a method used in linguistics for checking the correctness of sentences of natural languages. This method is modelled by restarting automata. Here we introduce and study a new type of restarting automaton, the socalled t-sRL-automaton, which is an RL-automaton that is rather restricted in that it has a window of size 1 only, and that it works under a minimal acceptance condition. On the other hand, it is allowed to perform up to t rewrite (that is, delete) steps per cycle. Here we study the gap-complexity of these automata. The membership problem for a language that is accepted by a t-sRL-automaton with a bounded number of gaps can be solved in polynomial time. On the other hand, t-sRL-automata with an unbounded number of gaps accept NP-complete languages. 1

Restarting automata can be seen as analytical variants of classical automata as well as of regulated rewriting systems. We study a measure for the degree of nondeterminism of (context-free) languages in terms of deterministic restarting automata that are (strongly) lexicalized. This measure is based on the number of auxiliary symbols (categories)

Automata with a restart operation are a special kind of the linear bounded automaton. They can model syntax analysis by reduction which consists in stepwise simpli cation of an extended sentence so that the (in)correctness of the sentence is not aected. An automaton with a restart operation is a one-tape device with a nite control and a read/write-window of xed length. We study several versions of automata with a restart operation and we show hierarchies with respect to the size of the read/write-window.

ABSTRACT Linear list automata constitute an interesting class of acceptors which has a remarkable `explicatory power ' w.r.t. the analysis of formal and natural languages. We consider a more general model where each automaton has a (fixed-size) look-ahead window attached to its head. We present a refinement of the Chomsky hierarchy, and display the classes of automata which can support bottomup analysis. The work is meant as a preparation for a further generalization, which will combine linear list automata and restarting automata. 1. Introduction We follow some previous studies of list automata (see [1], [5]) and introduce a generalized model- a two-way linear list automaton with a look-ahead window (LLA), and its subclasses defined by sets of allowed operations. The model with the lookahead window is more natural and useful for modelling the (reduction and syntactic) analysis of natural languages (compare [6], [7], [8], [3]), and for developing software tools for linguistic modelling.