1,260,300 research outputs found
Max Dehn, Axel Thue, and the Undecidable
This is a short essay on the roles of Max Dehn and Axel Thue in the
formulation of the word problem for (semi)groups, and the story of the proofs
showing that the word problem is undecidable.Comment: Definition of undecidability and unsolvability improve
Multidimensional Generalized Automatic Sequences and Shape-symmetric Morphic Words
An infinite word is S-automatic if, for all n>=0, its (n + 1)st letter is the
output of a deterministic automaton fed with the representation of n in the
considered numeration system S. In this extended abstract, we consider an
analogous definition in a multidimensional setting and present the connection
to the shape-symmetric infinite words introduced by Arnaud Maes. More
precisely, for d>=2, we state that a multidimensional infinite word x : N^d \to
\Sigma over a finite alphabet \Sigma is S-automatic for some abstract
numeration system S built on a regular language containing the empty word if
and only if x is the image by a coding of a shape-symmetric infinite word
Generic-case complexity, decision problems in group theory and random walks
We give a precise definition of ``generic-case complexity'' and show that for
a very large class of finitely generated groups the classical decision problems
of group theory - the word, conjugacy and membership problems - all have
linear-time generic-case complexity. We prove such theorems by using the theory
of random walks on regular graphs.Comment: Revised versio
Grouping Synonyms by Definitions
We present a method for grouping the synonyms of a lemma according to its
dictionary senses. The senses are defined by a large machine readable
dictionary for French, the TLFi (Tr\'esor de la langue fran\c{c}aise
informatis\'e) and the synonyms are given by 5 synonym dictionaries (also for
French). To evaluate the proposed method, we manually constructed a gold
standard where for each (word, definition) pair and given the set of synonyms
defined for that word by the 5 synonym dictionaries, 4 lexicographers specified
the set of synonyms they judge adequate. While inter-annotator agreement ranges
on that task from 67% to at best 88% depending on the annotator pair and on the
synonym dictionary being considered, the automatic procedure we propose scores
a precision of 67% and a recall of 71%. The proposed method is compared with
related work namely, word sense disambiguation, synonym lexicon acquisition and
WordNet construction
- …