We introduce tree stack automata as a new class of automata with storage and identify a restricted form of tree stack automata that recognises exactly the multiple context-free languages.

Given a set of n disjoint line segments in the plane, we show that it is always possible to form a tree with the endpoints of the segments such that each line segment is an edge of the tree, the tree has no crossing edges, and the maximum vertex degree of the tree is 3. Furthermore, there exist conngurations of line segments where any such tree requires degree 3. We provide an O(n log n) time a...

This paper concerns the task of removing redundant information from a given knowledge base, and restructuring it in the form of a tree, so as to admit efficient problem solving routines. We offer a novel approach which guarantees the removal of all redundancies that hide a tree structure. We develop a polynomial time algorithm that, given an arbitrary constraint network, generates a precise tre...

It is known that by iterating the look-ahead tree languages for deterministic topdown tree automata, more and more powerful recognizing devices are obtained. Let DR0 = DR, where DR is the class of all tree languages recognizable by deterministic top-down tree automata, and let, for n 1, DRn be the class of all tree languages recognizable by deterministic top-down tree automata with DRn 1 lookah...

This paper describes an algorithm of proof search for implicational formula in intuitionistic logic. It is based on a natural deduction style formulation of long normal form of simply typed -calculus. The algorithm returns a deduction tree, which becomes a proof if the formula is provable. When the formula is unprovable, a counter-model is constructed by identifying the repeated nodes in the de...

considering convergent product as an important manufacturing technology for digital products, we integrate functions and sub-functions using a comprehensive fuzzy mathematical optimization process. to form the convergent product, a web-based fuzzy network is considered in which a collection of base functions and sub-functions configure the nodes and each arc in the network is to be a link betwe...

Chvátal-Gomory and Gomory fractional cuts are well-known cutting planes for pure integer programming problems. Various methods for strengthening them are known, for example based on subadditive functions or disjunctive techniques. We present a new and surprisingly simple strengthening procedure, discuss its properties, and present some computational results.

We study a special class of binary trees. Our results have implications on Maker/Breaker games and SAT: We disprove a conjecture of Beck on positional games and construct an unsatisfiable k-CNF formula with few occurrences per variable, thereby improving a previous result by Hoory and Szeider and showing that the bound obtained from the Lovász Local Lemma is tight up to a constant factor. A (k,...

Many aspects of the relation of different decision tree and DNF complexity measures of Boolean functions have been more or less substantially explored. This paper adds a new detail to the picture: we prove that DNF tautologies with terms conflicting in one or two variables pairwise possess a tree-like structure. An equivalent reformulation of this result (adopting the terminology of [7, 8, 9]) ...

Consequently, an ADTree has nodes of two opposite types: attack nodes and defense nodes. The root of an ADTree represents the main goal of the attacker. Every node of an ADTree may have one or more children of the same type representing a refinement into sub-goals of the node’s goal. The refinement of a node can be either disjunctive or conjunctive. The goal of a disjunctively refined node is a...