Typing rule-based transformations over topological collections

Pattern-matching programming is an example of a rule-based programming style developed in functional languages. This programming style is intensively used in dialects of ML but is restricted to algebraic data-types. This restriction limits the field of application. However, as shown by Giavitto and Michel at RULE'02, case-based function definitions can be extended to more general data structures called topological collections. We show in this paper that this extension retains the benefits of the typed discipline of the functional languages. More precisely, we show that topological collections and the rule-based definition of functions associated with them fit in a polytypic extension of mini-ML where type inference is still possible

Production of Xylanase by Litter Degrading Fungal Species Using Agro-industrial Wastes as Substrates by Solid State Fermentation

ABSTRACT Xylan is a heterogeneous polysaccharide which are mainly constituted by β-1,4-linked-D-xylopyranose. Xylan forms a main constituent of hemicellulose, a plant polysaccharide. The most important enzyme in the xylan biodegradation is the endo-1, 4-β-xylanase (EC 3.2.1.8) that releases xylopyranose units. Agricultural wastes are found in staggering amounts in our country. These residues represent one of the most energy-rich resources available and when not properly discharged or used, add to environmental pollution. In the present study, thirty fungal species of various genera were isolated from litter soil. The objective of the study is to find the fungus that produces high titres of endo-β-1, 4-xylanase in solid state fermentation using various agro-industrial wastes as substrate. Three fungal species were selected and solid state fermentation was carried out. Aspergillus nidulans and Trichoderma viride produced higher enzyme production of 561.75 U/g and 446.25 U/g respectively when grown on rice bran. Penicillium frequentans produced the highest among the three producers when grown on paddy straw to an extent of 735 U/g. These results indicate that agro-industrial wastes can be used to produce xylanase and thus reduce the risk of environmental pollution

Balance machines: A new formalism for computing

The Balance Machine is a newly proposed natural computational model that consists of components resembling physical balances. The model has only one operation, “balancing”, which suffices in principle to perform universal computation. An interesting feature of the balance machine is its bidirectional operation: it can compute “forwards and backwards”, i.e. both a function and its partial inverse can be computed spontaneously using the same machine. Also, the machine exhibits a different kind of parallelism—a “bilateral parallelism”. The aim of this note is two–fold: To introduce a formalism for computing with balance machines—a convenient notation for representing the mechanical model on paper, and to demonstrate its expressive power by solving two NP–complete problems, namely, Set Partition and Knapsack. 1 Computing without knowing how to count Standard theoretical formalisms and programming languages of mainstream computer science influence us to think of computation mainly in terms of arithmetic/logical operation

Implementing Bead-Sort with P systems

Abstract. In this paper, we implement Bead–Sort, a natural sorting algorithm we introduced in [1], with the new, biochemically inspired Psystems.InBead–Sort, positive integers are represented by a set of beads (like those used in an Abacus). The beads representing integers to be sorted are allowed to slide through the rods of the Abacus. In this process, the smaller “numbers ” always emerge above the larger ones and this creates a natural comparison and thus a natural sorting action. This natural sorting phenomenon is “implemented ” with a special type of Psystem—atissue P system that computes by means of communication (using symport/antiport rules) only. Beads are represented by objects placed within membranes of a tissue P system; a rod is represented by a ‘group ’ of membranes that can communicate with one another by means of symport/antiport rules. The “flow ” of objects between the group of membranes representing a rod (using communication rules) reflects the actual flow of beads in the physical system