In the paper some combinatorial problems motivated by comma-free codes are considered. We describe these problems, give the most significant known results and methods used, present some new results and formulate open problems.

Any closed, connected Riemannian manifold M can be smoothly embedded by its Laplacian eigenfunction maps into Rm for some m. We call the smallest such m the maximal embedding dimension of M. We show that the maximal embedding dimension of M is bounded from above by a constant depending only on the dimension of M, a lower bound for injectivity radius, a lower bound for Ricci curvature, and a vol...

In this paper, we describe an innovative project where Web technologies are exploited to foster science learning in an integrated but mobile smart learning environment. Contextawareness is considered a crucial skill in science learning, therefore we imagined a solution to train students for context awareness by illustrating context gaps based on on-site observations and measurements. A componen...

We describe a novel parsing strategy we are employing for Chinese. We believe progress in Chinese parsing technology has been slowed by the excessive ambiguity that typically arises in pure context-free grammars. This problem has inspired a modified formalism that enhances our ability to write and maintain robust large grammars, by constraining productions with left/right contexts and/or nonter...

We introduce the first grammar-compressed representation of a sequence that supports searches in time that depends only logarithmically on the size of the grammar. Given a text T [1..u] that is represented by a (context-free) grammar of n (terminal and nonterminal) symbols and size N (measured as the sum of the lengths of the right hands of the rules), a basic grammar-based representation of T ...

We introduce a human-computer interaction system which collaborates with a user by providing feedback during user activities. The goal of the system is to help a user complete a high-level activity that has been represented hierarchically. While a user is performing the high-level activity, our system analyzes what sub-events a user has already completed and what sub-events are needed next in o...

This paper describes a system that performs hierarchical error recovery, and detects and corrects a single error in a sentence at the lexical, syntactic, and/or semantic levels. If the system is unable to repair an erroneous sentence on the assumption that it has a single error, a multiple error recovery system is invoked. The system employs a chart parsing algorithm and uses an augmented conte...

A context-free grammar G is ambiguous if there is a word that can be generated by G with at least two different derivation trees. Ambiguous grammars are often distinguished by their degree of ambiguity, which is the maximal number of derivation trees for the words generated by them. If there is no such upper bound G is said to be ambiguous of infinite degree. By considering how many derivation ...

Treebanks are a valuable resource for the training of parsers that perform automatic annotation of unseen data. It has been shown that changes in the representation of linguistic annotation have an impact on the performance of a certain annotation task. We focus on the task of Topological Field Parsing for German using Probabilistic Context-Free Grammars in the present research. We investigate ...

This article presents the central algorithm of an open system for grammar checking, based on deep parsing. The grammatical specification is a context-free grammar with flat feature structures. After a shared-forest analysis where feature agreement constraints are relaxed, error detection globally minimizes the number of corrections and alternative correct sentences are automatically proposed.