5 research outputs found
Shuffling posets on trajectories (technical report)
Choreographies describe possible sequences of interactions among a set of
agents. We aim to join two lines of research on choreographies: the use of the
shuffle on trajectories operator to design more expressive choreographic
languages, and the use of models featuring partial orders, to compactly
represent concurrency between agents. Specifically, in this paper, we explore
the application of the shuffle on trajectories operator to individual posets,
and we give a characterisation of shuffles of posets which again yield an
individual poset.Comment: 9 pages. Technical report of a paper to be published in the
conference proceedings of iFM 202
On Languages Generated by Signed Grammars
We consider languages defined by signed grammars which are similar to
context-free grammars except productions with signs associated to them are
allowed. As a consequence, the words generated also have signs. We use the
structure of the formal series of yields of all derivation trees over such a
grammar as a method of specifying a formal language and study properties of the
resulting family of languages.Comment: In Proceedings NCMA 2023, arXiv:2309.0733
State-deterministic Finite Automata with Translucent Letters and Finite Automata with Nondeterministically Translucent Letters
Deterministic and nondeterministic finite automata with translucent letters
were introduced by Nagy and Otto more than a decade ago as Cooperative
Distributed systems of a kind of stateless restarting automata with window size
one. These finite state machines have a surprisingly large expressive power:
all commutative semi-linear languages and all rational trace languages can be
accepted by them including various not context-free languages. While the
nondeterministic variant defines a language class with nice closure properties,
the deterministic variant is weaker, however it contains all regular languages,
some non-regular context-free languages, as the Dyck language, and also some
languages that are not even context-free. In all those models for each state,
the letters of the alphabet could be in one of the following categories: the
automaton cannot see the letter (it is translucent), there is a transition
defined on the letter (maybe more than one transitions in nondeterministic
case) or none of the above categories (the automaton gets stuck by seeing this
letter at the given state and this computation is not accepting).
State-deterministic automata are recent models, where the next state of the
computation determined by the structure of the automata and it is independent
of the processed letters. In this paper our aim is twofold, on the one hand, we
investigate state-deterministic finite automata with translucent letters. These
automata are specially restricted deterministic finite automata with
translucent letters.
In the other novel model we present, it is allowed that for a state the set
of translucent letters and the set of letters for which transition is defined
are not disjoint. One can interpret this fact that the automaton has a
nondeterministic choice for each occurrence of such letters to see them (and
then erase and make the transition) or not to see that occurrence at that time.
Based on these semi-translucent letters, the expressive power of the automata
increases, i.e., in this way a proper generalization of the previous models is
obtained.Comment: In Proceedings AFL 2023, arXiv:2309.0112