Silent Transitions in Automata with Storage

We consider the computational power of silent transitions in one-way automata with storage. Specifically, we ask which storage mechanisms admit a transformation of a given automaton into one that accepts the same language and reads at least one input symbol in each step. We study this question using the model of valence automata. Here, a finite automaton is equipped with a storage mechanism that is given by a monoid. This work presents generalizations of known results on silent transitions. For two classes of monoids, it provides characterizations of those monoids that allow the removal of \lambda-transitions. Both classes are defined by graph products of copies of the bicyclic monoid and the group of integers. The first class contains pushdown storages as well as the blind counters while the second class contains the blind and the partially blind counters.Comment: 32 pages, submitte

Accepting splicing systems with permitting and forbidding words

Abstract: In this paper we propose a generalization of the accepting splicingsystems introduced in Mitrana et al. (Theor Comput Sci 411:2414?2422,2010). More precisely, the input word is accepted as soon as a permittingword is obtained provided that no forbidding word has been obtained sofar, otherwise it is rejected. Note that in the new variant of acceptingsplicing system the input word is rejected if either no permitting word isever generated (like in Mitrana et al. in Theor Comput Sci 411:2414?2422,2010) or a forbidding word has been generated and no permitting wordhad been generated before. We investigate the computational power ofthe new variants of accepting splicing systems and the interrelationshipsamong them. We show that the new condition strictly increases thecomputational power of accepting splicing systems. Although there areregular languages that cannot be accepted by any of the splicing systemsconsidered here, the new variants can accept non-regular and even non-context-free languages, a situation that is not very common in the case of(extended) finite splicing systems without additional restrictions. We alsoshow that the smallest class of languages out of the four classes definedby accepting splicing systems is strictly included in the class of context-free languages. Solutions to a few decidability problems are immediatelyderived from the proof of this result

Passagierdampfer als Hilfskreuzer: kurze Geschichte der Entwicklung einer Schiffsgattung

To date there is no cohesive historical account of the international development of the auxiliary cruiser, and the scattered investigations of various single aspects of this ship category do not add up to a comprehensive survey. These were the circumstances discovered by the author as, upon request of the editor of this publication, he undertook to provide an introduction to the report by Captain Meyer of the only voyage of the "Kaiser Wilhelm der Grosse" as an auxiliary cruiser (see the following article). The first task was thus to gain an overall impression of this history. "Auxiliary cruisers", as defined here, were passenger steamships kept ready for battle by large shipping companies in countries with significant naval power. These ships were technically equipped for the installation of weapons, and their conversion could be carried out within a few days. The auxiliary cruiser was first to put into service by the Russians, who felt threatened by the British Royal Navy after the Russian-Turkish Balkan War. At that time a newly established shipping company, later called the "Russian Voluntary Fleet", bought three steamships from the Hamburg-America Line and had them converted for combat purposes. By the turn of the century, this originally Russian idea had been adopted by all of the world's Iarge navies . This brief study also touches on the various attempt worldwide to incorporate the legal status of the ship type "auxiliary cruiser" into international public and military law. Because of geopolitically based conflicts of interest between the naval powers, these endeavours were only partially successful. ln conclusion the author examines the auxiliary cruiser concept of the Imperial German Navy, whose goal it was to interfere with and impair the enemy's overseas commerce. The express Iiners originally designated for this purpose, however, were for various reasons inconceivably ill-suited to it. As early as 1915 the German Navy proceeded to commission cargo vessels as auxiliary cruisers, as they were inconspicuous and easier to supply. This was then the mode of operation employed by the navy during World War II

Splicing Grammar Systems

The aim of this paper is to bring together two new and powerful tools: on the one hand, the splicing operation as a basic operation on DNA sequences and, on the  other hand, the parallelism and communication features in grammar systems. As expected, the result of the above combination is a very powerful mechanism, leading to a new characterization of recursively enumerable languages

Net Computing con processori evolutivi

n generale capire come la natura “calcola” a livello cellulare, ammesso che l’evoluzione sia un processo computazionale. Più specificamente proporremo nuovi modelli di calcolo ispirati al funzionamento di comunità di cellule, che suggeriscono nuovi supporti (hardware e software) per la computazione, nuovi modi di organizzare i dati e manipolare queste nuove strutture di dati, in una parola, nuovi paradigmi di calcolo. In una visione generale, la cella può essere trattata come una macchina molecolare che ha input forniti da recettori che riconoscono i loro legami molecolari stereo specifici, mentre le transizioni di stato e gli output sono determinati dai gradienti di concentrazioni metaboliche. Gli enzimi nella cella accendono e spengono reazioni chimiche come i transistor fanno con la corrente elettrica nei circuiti di un computer. Si postula che le funzioni di interruttore degli enzimi siano guidate dalla conformazione specifica delle loro sequenze. Perciò è possibile in teoria disegnare strutture computazionali basate sui polimeri utilizzando le reazioni meccanochimiche di attivazione ed espressione dei geni. Scopo del progetto è di definire un modelllo matematico che dovrebbe tener conto dell’energia libera e dell’informazione genetica postulata necessaria e sufficiente per dirigere tutti i processi molecolari diretti ad uno scopo nella cellula

RETI DI PROCESSORI DI IMMAGINI CELL-LIKE: CALCOLO, COMPLESSITÀ E ASPETTI DI SIMULAZIONE

Questo progetto è incentrato sui modelli di calcolo bio-ispirati astratti da reti molto complesse di sistemi viventi. Il suo obiettivo è quello di investigare diversi aspetti di reti di processori cell-like su parole bidimensionali (immagini), in particolare incentrato sulle connessioni tra modelli teorici e reti naturali (biologici). I temi principali sono: - Gli aspetti computazionali (potenza di calcolo, complessità strutturale e descrittiva). - Aspetti di applicazioni (simulazione, realizzazione fisica, risultati sperimentali, addestramento). Questo progetto di ricerca è destinato ad essere un contributo sia al Global Computing (che comprende reti neurali, automi cellulari, ecc.) che al Computing Bio-ispirato (come parte del Computing naturale): un nuovo campo interdisciplinare che si trova al crocevia tra la matematica, l'informatica, la biologia molecolare e la linguistica

Superposition Based on Watson-Crick-like Complementarity

In this paper we propose a new formal operation on words and languages, called superposition. By this operation, based on a Watson–Crick-like complementarity, we can generate a set of words, starting from a pair of words, in which the contribution of a word to the result need not be one subword only, as happens in classical bio-operations of DNA computing. Specifically, starting from two single stranded molecules x and y such that a suffix of x is complementary to a prefix of y, a prefix of x is complementary to a suffix of y, or x is complementary to a subword of y, a new word z, which is a prolongation of x to the right, to the left, or to both, respectively, is obtained by annealing. If y is complementary to a subword of x, then the result is x. This operation is considered here as an abstract operation on formal languages. We relate it to other operations in formal language theory and we settle the closure properties under this operation of classes in the Chomsky hierarchy. We obtain a useful result by showing that unrestricted iteration of the superposition operation, where the "parents" in a subsequent iteration can be any words produced during any preceding iteration step, is equivalent to restricted iteration, where at each step one parent must be a word from the initial language. This result is used for establishing the closure properties of classes in the Chomsky hierarchy under iterated superposition. Actually, since the results are formulated in terms of AFL theory, they are applicable to more classes of languages. Then we discuss "adult" languages, languages consisting of words that cannot be extended by further superposition, and show that this notion might bring us to the border of recursive languages. Finally, we consider some operations involved in classical DNA algorithms, such as Adleman's, which might be expressed through iterated superposition