separating k separated ence graph languages an ence graph grammar is k separated k 1 if the distance between any two nonterminal nodes in any of its sentential forms is at least k let sepk denote the class of graph languages generated by k separated grammars then sep1 sep2 is the class of ence boundary ence graph languages and so sep2 sep1 recently engelfriet 1991 showed that sep3 sep2 and conjectured that in fact sepk 1 sepk for each k 1 we prove this conjecture affirmatively

complexity of normal form grammars abstract various types of grammars can be used to describe context free languages such are context free grammars and their normal form restrictions rewriting of a context free grammar to an equivalent grammar in required normal form can cause a change of parameters of the grammar such as the number of rules the number of nonterminals etc greibach normal form grammars and position restricted grammars will be investigated from the point of view of descriptional complexity of context free languages

fuzzy filters of mtl algebras characterizations of fuzzy filters in mtl algebras are given the fuzzy filter generated by a fuzzy set is considered the notion of boolean fuzzy filters and mv fuzzy filters are introduced and related properties are investigated a condition for a fuzzy filter to be boolean is provided a characterization of a boolean fuzzy filter is given a congruence relation on a mtl algebra induced by a fuzzy filter is established and we show that the set of all congruence relations induced by a fuzzy filter is a completely distributive lattice

residuated skew lattices abstract skew lattices are one of the most successful non commutative generalizations of lattices motivated by the study of residuation on ordered structures and that of skew boolean algebras and skew heyting algebras in this paper we introduce the concept of residuated skew lattices as a new non commutative version of residuated lattices the axiomatization and localization for residuated skew lattices are obtained moreover a characterization of residuation on skew lattices via adjointness is presented meanwhile three special subvarieties distributive residuated skew lattices skew mtl algebras and skew bl algebras are investigated in particular we show that every skew heyting algebra is a reduct of a special residuated skew lattice

fuzzy filters of bl algebras the aim of this paper is to introduce the notions of fuzzy filters fuzzy prime filters and the cosets of a fuzzy filter in bl algebras and investigate some of their properties the fuzzy filter generated by a fuzzy set is discussed some characterizations of fuzzy filters and fuzzy prime filters are derived the extension theorem of fuzzy prime filters and the fuzzy prime filters theorem are established finally we prove that the algebra l f which is the set of all cosets of f is a bl algebra and is isomorphic to the bl algebra l ff 1 where ff 1 x l f x f 1 moreover each bl algebra l is a subdirect product of linearly ordered bl algebras l fi i where fi i are fuzzy prime filters of l

fuzzy logics as the logics of chains the paper proposes a formal delimitation of the class of fuzzy logics and answers some objections that can be raised against the definition the focus is put on informal and motivational aspects of the problem

a comprehensive study of fuzzy covering based rough set models definitions properties and interrelationships abstract fuzzy covering based rough set models are hybrid models using both rough set and fuzzy set theory the former is often used to deal with uncertain and incomplete information while the latter is used to describe vague concepts the study of fuzzy rough set models has provided very good tools for machine learning algorithms such as feature and instance selection in this article we discuss different types of dual fuzzy rough set models which all consider fuzzy coverings in particular we study two models using non nested level based representation of fuzziness in addition to the study of the theoretical properties for each model interrelationships between the different models are discussed resulting in a hasse diagram of fuzzy covering based rough set models for a finite fuzzy covering an imtl t norm and its residual implicator

another paraconsistent algebraic semantics for lukasiewicz pavelka logic abstract as recently proved in a previous work of turunen tsoukias and ozturk starting from an evidence pair a b on the real unit square and associated with a propositional statement we can construct evidence matrices expressed in terms of four values t f k u that respectively represent the logical valuations true false contradiction both true and false and unknown neither true nor false regarding the statement the components of the evidence pair a b are to be understood as evidence for and against respectively moreover the set of all evidence matrices can be equipped with an injective mv algebra structure thus the set of evidence matrices can play the role of truth values of a lukasiewicz pavelka fuzzy logic a rich and applicable mathematical foundation for fuzzy reasoning and in such a way that the obtained new logic is paraconsistent in this paper we show that a similar result can be also obtained when the evidence pair a b is given on the real unit triangle since the real unit triangle does not admit a natural mv structure we introduce some mathematical results to show how this shortcoming can be overcome and another injective mv algebra structure in the corresponding set of evidence matrices is obtained also we derive several formulas to explicitly calculate the evidence matrices for the operations associated to the usual connectives

on local triangle algebras abstract in this paper we have introduced the notion of local and semilocal triangle algebras and propose the theorems that characterize these algebraic structures additionally we have established the new properties of these algebraic structures and discussed the relations between local triangle algebras and some interval valued residuated lattice ivrl filters such as n fold ivrl extended integral filters and ivrl extended maximal filters the obtained results proved that the mtl triangle algebra is a subdirect product of local triangle algebras moreover a correlation was observed between the set of the dense elements and local triangle algebras finally semilocal triangle algebras were introduced and assessed in detail and an association was observed between the semilocal triangle algebras and quotient triangle algebras

recursive markov chains stochastic grammars and monotone systems of nonlinear equations we define recursive markov chains rmcs a class of finitely presented denumerable markov chains and we study algorithms for their analysis informally an rmc consists of a collection of finite state markov chains with the ability to invoke each other in a potentially recursive manner rmcs offer a natural abstract model for probabilistic programs with procedures they generalize in a precise sense a number of well studied stochastic models including stochastic context free grammars scfg and multi type branching processes mt bp we focus on algorithms for reachability and termination analysis for rmcs what is the probability that an rmc started from a given state reaches another target state or that it terminatesq these probabilities are in general irrational and they arise as least fixed point solutions to certain monotone systems of nonlinear equations associated with rmcs we address both the qualitative problem of determining whether the probabilities are 0 1 or in between and the quantitative problems of comparing the probabilities with a given bound or approximating them to desired precision we show that all these problems can be solved in pspace using a decision procedure for the existential theory of reals we provide a more practical algorithm based on a decomposed version of multi variate newton s method and prove that it always converges monotonically to the desired probabilities we show this method applies more generally to any monotone polynomial system we obtain polynomial time algorithms for various special subclasses of rmcs among these for scfgs and mt bps equivalently for 1 exit rmcs the qualitative problem can be solved in p time for linearly recursive rmcs the probabilities are rational and can be computed exactly in p time we show that our pspace upper bounds cannot be substantially improved without a breakthrough on long standing open problems the square root sum problem and an arithmetic circuit decision problem that captures p time on the unit cost rational arithmetic ram model we show that these problems reduce to the qualitative problem and to the approximation problem to within any nontrivial error for termination probabilities of general rmcs and to the quantitative decision problem for termination extinction of scfgs mt bps

the pseudo linear semantics of interval valued fuzzy logics triangle algebras are equationally defined structures that are equivalent with certain residuated lattices on a set of intervals which are called interval valued residuated lattices ivrls triangle algebras have been used to construct triangle logic tl a formal fuzzy logic that is sound and complete w r t the class of ivrls in this paper we prove that the so called pseudo prelinear triangle algebras are subdirect products of pseudo linear triangle algebras this can be compared with mtl algebras prelinear residuated lattices being subdirect products of linear residuated lattices as a consequence we are able to prove the pseudo chain completeness of pseudo linear triangle logic ptl an axiomatic extension of tl introduced in this paper this kind of completeness is the analogue of the chain completeness of monoidal t norm based logic mtl this result also provides a better insight in the structure of triangle algebras it enables us amongst others to prove properties of pseudo prelinear triangle algebras more easily it is known that there is a one to one correspondence between triangle algebras and couples l a in which l is a residuated lattice and a an element in that residuated lattice we give a schematic overview of some properties of pseudo prelinear triangle algebras and a number of others that can be imposed on a triangle algebra and the according necessary and sufficient conditions on l and a

a polynomial algorithm for deciding bisimilarity of normed context free processes the previous best upper bound on the complexity of deciding bisimilarity between normed context free processes due to huynh and tian is that the problem lies in the second level of the polynomial hierarchy their algorithm guesses a proof of equivalence and validates this proof in polynomial time using oracles freely answering questions which are in np in this paper we improve on this result by presenting a polynomial time algorithm which solves this problem as a corollary we have a polynomial algorithm for the equivalence problem for simple context free grammars

l a l b decidability results from complete formal systems abstract the equivalence problem for deterministic pushdown automata is shown to be decidable we exhibit a complete formal system for deducing equivalent pairs of deterministic rational boolean series on the alphabet associated with a dpda m we then extend the result to deterministic pushdown transducers from a free monoid into an abelian group a general algebraic and logical framework inspired by harrison et al theoret comput sci 9 1979 173 205 conrcelle theoret comput sci 6 1978 255 279 and meitus kybernetika 5 1989 14 25 in russian is developed

boundary nlc graph grammars basic definitions normal forms and complexity node label controlled nlc grammars are graph grammars operating on node labeled undirected graphs which rewrite single nodes only and establish connections between the embedded graph and the neighbors of the rewritten node on the basis of the labels of the involved nodes only they define possibly infinite languages of undirected node labeled graphs or if we just omit the labels languages of unlabeled graphs here we consider a restriction of nlc grammars so called boundary nlc bnlc grammars distinguished by the property that whenever in a graph already generated two nodes may be rewritten then these nodes are not adjacent the graph languages generated by this type of grammars are called bnlc languages although we show that this restriction leads to a smaller class of languages still enough generative power remains to define interesting graph languages for example trees complete bipartite graphs maximal outerplanar graphs k trees graphs of bandwidth k graphs of cyclic bandwidth k graphs of binary tree bandwidth k graphs of cutwidth k always for a fixed positive integer k turn out all to be bnlc languages we prove a number of normal forms for bnlc grammars and then we indicate their usefulness by various applications in particular we show that for connected graphs of bounded degree the membership problem for bnlc languages is solvable in deterministic polynomial time

on greibach normal form construction abstract we present an algorithm which given an arbitrary e free and chain free context free grammar produces an equivalent context free grammar in greibach normal form gnf this algorithm is a generalization of an algorithm recently presented by ehrenfeucht and rozenberg using this algorithm the well known gnf construction of rosenkrantz can be obtained furthermore it is possible to rewrite a given context free grammar by a gnf grammar which has at most twice as much nonterminals as the original grammar this result is shown to be optimal with respect to the number of nonterminals

on v filters and normal v filters of a residuated lattice with a weak vt operator in this paper we study further the filter theory of residuated lattices first we discuss the concepts of filters and normal filters of residuated lattices and propose some equivalent conditions for them then we introduce and investigate the notions of v filter and normal v filter of a residuated lattice with a weak vt operator and lay bare the formulas for calculating the v filters and the normal v filters generated by subsets finally we show that the lattices of v filters and normal v filters of a residuated lattice with a vt operator are both complete brouwerian lattices

growth motion and 1 parameter families of symmetry sets associated to every plane curve there is the locus of centres of circles bitangent to that curve the so called symmetry set of the curve we can view this set as the spine of our curve which can be recovered by taking the envelope of circles of varying radii along this spine varying the symmetry set in some isotopy while keeping the radius function fixed may be viewed as crudely modelling motion of the original curve viewed as a biological object fixing the symmetry set and varying the radius function can be considered to model growth crudely in this paper we shall describe the generic changes in the curves which take place in the process of growth and motion and outline the corresponding results for spheres centred on a space curve we also use the idea of a stratified morse function to describe the generic changes which occur in one parameter families of full bifurcation sets in the plane applying this to the bifurcation set of distance squared functions we find all the transitions of a symmetry set and evolute which occur in a generic isotopy of a plane curve

filters of residuated lattices and triangle algebras an important concept in the theory of residuated lattices and other algebraic structures used for formal fuzzy logic is that of a filter filters can be used amongst others to define congruence relations specific kinds of filters include boolean filters and prime filters in this paper we define several different filters of residuated lattices and triangle algebras and examine their mutual dependencies and connections triangle algebras characterize interval valued residuated lattices

pseudo bck algebras as partial algebras it is well known that the representation of several classes of residuated lattices involves lattice ordered groups an often applicable method to determine the representing group or groups from a residuated lattice is based on partial algebras the monoidal operation is restricted to those pairs that fulfil a certain extremality condition and else left undefined the subsequent construction applied to the partial algebra is easy transparent and leads directly to the structure needed for representation in this paper we consider subreducts of residuated lattices the monoidal and the meet operation being dropped the resulting algebras are pseudo bck semilattices assuming divisibility we can pass on to partial algebras also in this case to reconstruct the underlying group structure from this partial algebra if applicable is again straightforward we demonstrate the elegance of this method for two classes of pseudo bck semilattices semilinear divisible pseudo bck algebras and cone algebras

the standard completeness of interval valued monoidal t norm based logic in this paper we prove the strong standard completeness of interval valued monoidal t norm based logic ivmtl and some of its extensions for other extensions we show that they are not strong standard complete we also give a local deduction theorem for ivmtl and other extensions of interval valued monoidal logic similar results are obtained for interval valued fuzzy logics expanded with baaz s delta

computing exact aspect graphs of curved objects algebraic surfaces this article presents an algorithm for computing the exact aspect graph of an opaque solid bounded by a smooth algebraic surface orthographic projection is assumed the algorithm is based on a catalog of visual events available from singularity theory it uses curve tracing cell decomposition homotopy continuation and ray tracing to construct the regions of the view sphere delineated by visual event curves the algorithm has been fully implemented and examples are presented

singularities of illuminated surfaces we study local singularities that appear in pictures of illuminated objects we suppose there is only one light source and we look at the shadow it casts on the surface we focus on the frontier between shadow and light in the visual plane these curves interact with the apparent contour of the surface the search of generic situations translates into a classification problem in singularity theory we are thus able to give the list of the six stable and generic views of illuminated surfaces

mathematical fuzzy logic as a tool for the treatment of vague information the paper considers some of the main trends of the recent development of mathematical fuzzy logic as an important tool in the toolbox of approximate reasoning techniques particularly the focus is on fuzzy logics as systems of formal logic constituted by a formalized language by a semantics and by a calculus for the derivation of formulas besides this logical approach also a more algebraic approach is discussed and the paper ends with some hints toward applications which are based upon these theoretical considerations

an easy proof of greibach normal form we present an algorithm which given an arbitrary a free context free grammar produces an equivalent context free grammar in 2 greibach normal form the upper bound on the size of the resulting grammar in terms of the size of the initially given grammar is given our algorithm consists of an elementary construction while the upper bound on the size of the resulting grammar is not bigger than the bounds known for other algorithms for converting context free grammars into equivalent context free grammars in greibach normal form

node replacement graph languages squeezed with chains trees and forests we present results on language theoretic properties such as closure membership and other decision properties of node replacement graph languages such as nlc b nlc and lin nlc languages squeezed with chains trees and forests

language equivalence of probabilistic pushdown automata we study the language equivalence problem for probabilistic pushdown automata ppda and their subclasses we show that the problem is interreducible with the multiplicity equivalence problem for context free grammars the decidability of which has been open for several decades interreducibility also holds for ppda with one control state in contrast for the case of a one letter input alphabet we show that ppda language equivalence and hence multiplicity equivalence of context free grammars is in pspace and at least as hard as the polynomial identity testing problem

on fuzzy filters of pseudo bl algebras abstract we introduce the concept of fuzzy filters of pseudo bl algebras and obtain some of their important properties we further give several kinds of fuzzy filters such as fuzzy boolean filter fuzzy normal filter fuzzy prime filter fuzzy ultrafilter and fuzzy obstinate filter and discuss the relations among the above fuzzy filters we establish the prime fuzzy filter theorem in pseudo bl algebras by studying the relation between fuzzy boolean filter and fuzzy normal filter in pseudo bl algebras we solve an open problem that whether or not every boolean filter is normal in pseudo bl algebras

on residuated lattices with left and right internal state abstract in this paper notions of left and right state operators on residuated lattices are introduced and some related properties of such operators are investigated filters and normal filters generated by a subset in a state residuated lattice are characterized and it is shown that the lattice of filters forms a frame subdirectly irreducible state residuated lattices are characterized the notion of state coannihilator is introduced and a connection between them and galois connection is established finally it is shown that the set of state coannihilators forms a complete boolean algebra

decision problems for word hyperbolic semigroups abstract this paper studies decision problems for semigroups that are word hyperbolic in the sense of duncan and gilman a fundamental investigation reveals that the natural definition of a word hyperbolic structure has to be strengthened slightly in order to define a unique semigroup up to isomorphism this does not alter the class of word hyperbolic semigroups the isomorphism problem is proven to be undecidable for word hyperbolic semigroups in contrast to the situation for word hyperbolic groups it is proved that it is undecidable whether a word hyperbolic semigroup is automatic asynchronously automatic biautomatic or asynchronously biautomatic these properties do not hold in general for word hyperbolic semigroups it is proved that the uniform word problem for word hyperbolic semigroups is solvable in polynomial time improving on the previous exponential time algorithm algorithms are presented for deciding whether a word hyperbolic semigroup is a monoid a group a completely simple semigroup a clifford semigroup or a free semigroup

quasi rocking real time pushdown automata a pushdown automaton pda is quasi rocking if it preserves the stack height for no more than a bounded number of consecutive moves every pda can be transformed into an equivalent one that is quasi rocking and real time and every finite turn one turn pda can be transformed into an equivalent one that is quasi rocking or real time the quasi rocking quasi rocking in the increasing mode and quasi rocking in the decreasing mode real time restriction in finite turn one turn pdas coincides with the double greibach reverse greibach and greibach form in nonterminal bounded linear context free grammars this provides complete grammatical characterizations of quasi rocking and or real time finite turn and one turn pdas and together with known relations and other relations proved in the present paper yields an extended hierarchy of pda languages basic decision properties for pdas can be stated in stronger forms by using the quasi rocking and real time restrictions and their undecidability decidability status rests on the way pdas quasi rock

on the complexity of numerical analysis we study two quite different approaches to understanding the complexity of fundamental problems in numerical analysis a the blum shub smale model of computation over the reals and b a problem we call the generic task of numerical computation which captures an aspect of doing numerical computation in floating point similar to the long exponent model that has been studied in the numerical computing community we show that both of these approaches hinge on the question of understanding the complexity of the following problem which we call posslp given a division free straight line program producing an integer n decide whether n 0 in the blum shub smale model polynomial time computation over the reals on discrete inputs is polynomial time equivalent to posslp when there are only algebraic constants we conjecture that using transcendental constants provides no additional power beyond nonuniform reductions to posslp and we present some preliminary results supporting this conjecture the generic task of numerical computation is also polynomial time equivalent to posslp we prove that posslp lies in the counting hierarchy combining this with work of tiwari we obtain that the euclidean traveling salesman problem lies in the counting hierarchy the previous best upper bound for this important problem in terms of classical complexity classes being pspace in the course of developing the context for our results on arithmetic circuits we present some new observations on the complexity of the arithmetic circuit identity testing acit problem in particular we show that if n is not ultimately easy then acit has subexponential complexity

characterizations and new subclasses of i filters in residuated lattices abstract filters play an important role in studying logical systems and the related algebraic structures various filters have been proposed in the literature in this paper we aim to develop a unifying definition for some specific filters called i filters which provide us with a meaningful method to study these filters and corresponding logical algebras in particular trivial characterizations of i filters non trivial characterizations of classes of i filters such as implicative fantastic and boolean filters and characterizations of homologous logical algebras are obtained next three new types of i filters named divisible filters strong and n contractive filters in residuated lattices are introduced particularly it is verified that n fold implicative bl algebras and n contractive bl algebras coincide finally we investigate the relationships between these specific i filters it is shown that a filter is a fantastic filter if and only if it is both a divisible filter and a regular filter

double greibach operator grammars every context free grammar can be transformed into one in double greibach operator form that satisfies both double greibach form and operator form examination of the expressive power of various well known subclasses of context free grammars in double greibach and or operator form yields an extended hierarchy of language classes basic decision properties such as equivalence can be stated in stronger forms via new classes of languages in this hierarchy

triangle algebras a formal logic approach to interval valued residuated lattices in this paper we introduce triangle algebras a variety of residuated lattices equipped with approximation operators and with a third angular point u different from 0 and 1 we show that these algebras serve as an equational representation of interval valued residuated lattices ivrls furthermore we present triangle logic tl a system of many valued logic capturing the tautologies of ivrls triangle algebras are used to cast the essence of using closed intervals of l as truth values into a set of appropriate logical axioms our results constitute a crucial first step towards solving an important research challenge the axiomatic formalization of residuated t norm based logics on l i the lattice of closed intervals of 0 1 in a similar way as was done for formal fuzzy logics on the unit interval

interpreting line drawings of curved objects in this thesis we study the problem of interpreting line drawings of scenes composed or opaque regular solid objects bounded by piecewise smooth surfaces with no markings or texture on them it is assumed that the line drawing has been formed by orthographic projection of such a scene under general viewpoint that the line drawing is error free and that there are no lines due to shadows or specularities our definition implicitly excludes laminae wires and the apices of cones a major component of the interpretation of line drawings is line labelling by line labelling we mean a classification of each image curve as corresponding to either a depth or orientation discontinuity in the scene and b further subclassification of each kind of discontinuity for a depth discontinuity we determine whether it is a limb a locus of points on the surface where the line of sight is tangent to the surface or an occluding edge a tangent plane discontinuity of the surface for an orientation discontinuity we determine whether it corresponds to a convex or concave edge this thesis presents the first mathematically rigorous scheme for labelling line drawings of the class of scenes described by analysing the projection of the neighborhoods of different kinds of points on a piecewise smooth surface we are able to catalog all local labelling possibilities for the different types of junctions in a line drawing an algorithm is developed which utilizes this catalog to determine all legal labellings of the line drawing a local minimum complexity rule at each vertex select those labellings which correspond to the minimum number of faces meeting at the vertex is used in order to prune highly counter intuitive interpretations the labelling scheme was implemented and tested on a number of line drawings the labellings obtained are few and by and large in accordance with human interpretations

a new approach for classification of filters in residuated lattices in the mathematical literature many types of filters in residuated lattices or in special classes of residuated lattices bl algebras mtl algebras etc have been studied consequently many names have been proposed for these types of filters boolean filters heyting filters implicative filters positive implicative filters fantastic filters easy filters etc this multiplicity of names for the filters makes it very difficult to study them and the connections between them to avoid this inconvenience in this paper we propose a new approach for the study of these filters in residuated lattices in order to be easily accessible to the readers we also present a unified treatment of some particular results about filters in residuated lattices theorem 16 corollary 17

radicals in mtl algebras we study some special sets in mtl algebras the notion of the radical of a filter in mtl algebras is defined and several characterizations of the radical of a filter are given the sets of dense elements and double complemented elements in mtl algebras are defined and we state and prove some theorems on the properties of these sets and filters of mtl algebras we also prove that the radical of a positive implicative filter of an mtl algebra is a subset of double complemented elements

griebach normal form transformation revisited we develop a new method for placing a given context free grammar into greibach normal form with only polynomial increase of its size starting with an arbitrarye free context free grammarg we transformginto an equivalent context free grammarhin extended greibach normal form i e in addition to rules fulfilling the greibach normal form properties the grammar can have chain rules the size ofhwill beo g 3 where g is the size ofg moreover in the case thatgis chain rule free hwill be already in greibach normal form ifhis not chain rule free then we use the standard method for chain rule elimination for the transformation ofhinto greibach normal form the size of the constructed grammar iso g 4

boolean filters and positive implicative filters of residuated lattices the aim of this paper is to introduce the notions of boolean filters and positive implicative filters in residuated lattices and to investigate their properties several characterizations of boolean filters and positive implicative filters are derived the extension theorems of implicative filters and positive implicative filters are obtained the relations among boolean filters implicative filters and positive implicative filters are investigated and it is proved that boolean filters are equivalent to implicative filters and that every boolean filter is a positive implicative filter but the converse may not be true furthermore the conditions under which a positive implicative filter is a boolean filter are established

monoidal t norm based logic towards a logic for left continuous t norms hajek s bl logic is the fuzzy logic capturing the tautologies of continuous t norms and their residua in this paper we investigate a weaker logic mtl which is intended to cope with the tautologies of left continuous t norms and their residua the corresponding algebraic structures mtl algebras are defined and completeness of mtl with respect to linearly ordered mtl algebras is proved besides several schematic extensions of mtl are also considered as well as their corresponding predicate calculi

fuzzy filters and fuzzy prime filters of bounded r l monoids and pseudo bl algebras the logical foundations of processes handling uncertainty in information use some classes of algebras as algebraic semantics the sets of provable formulas in corresponding inference systems from the point of view of uncertain information can be described by fuzzy filters of those algebraic semantics bounded residuated lattice ordered monoids email protected monoids are a common generalization of pseudo bl algebras and consequently of pseudo mv algebras and heyting algebras i e algebras behind fuzzy and intuitionistic reasoning in the paper we introduce and investigate fuzzy filters of bounded email protected monoids and fuzzy prime filters of pseudo bl algebras

linear graph grammars power and complexity abstract a graph grammar is linear if it generates graphs with at most one nonterminal node linear graph grammars can simulate nonterminal bounded graph grammars which generate graphs with a bounded number of nonterminal nodes and derivation bounded graph grammars if a linear graph language contains connected graphs of bounded degree only then it is in nspace log n these results are shown for graph grammars with neighbourhood controlled embedding and with dynamic edge relabeling ence grammars

fuzzy neighborhood operators based on fuzzy coverings in many data mining processes neighborhood operators play an important role as they are generalizations of equivalence classes which were used in the original rough set model of pawlak in this article we introduce the notion of fuzzy neighborhood system of an object based on a given fuzzy covering as well as the notion of the fuzzy minimal and maximal descriptions of an object moreover we extend the definition of four covering based neighborhood operators as well as six derived coverings discussed by yao and yao to the fuzzy setting we combine these fuzzy neighborhood operators and fuzzy coverings and prove that only sixteen different fuzzy neighborhood operators are obtained moreover we study the partial order relations between those sixteen operators

a hierarchy of ence families of graph languages abstract even though ence and its subclasses have been studied intensively their inclusion relations are not completely known this paper proves some unknown relations among ence families of graph languages which yield together with other known relations a solid hierarchy of graph languages that completely determines equivalence proper inclusion and incomparability among nlc nce enlc ence and their boundary linear and apex subclasses the bottom level of this hierarchy i e lin a nlc contains an np complete graph language

categorial dependency grammars categorial dependency grammars cdgs are classical categorial grammars extended by oriented polarized valencies at the same time cdgs represent a class of completely lexicalized dependency grammars they express both projective and non projective dependencies cdgs generate non context free languages at that they are parsed in polynomial time under realistic conditions cdgs possess a normal form that is analogous to greibach normal form for cf grammars cdg languages are closed under almost all afl operations and are accepted by a special class of push down automata with independent counters

infinitely distributive t norms on complete lattices and pseudo complements in this paper we have introduced the concepts of t prime element t prime radical element and t semi prime element and have studied their properties we have investigated the construction methods of new infinitely distributive t norms from given infinitely distributive t norms by means of t prime elements and pseudo complements if every element of l is t prime radical element then we show that l is a complete brouwerian lattice and email protected if l is an algebraic lattice t is a t norm on l and every compact element of l is idempotent then we obtain that email protected we show that l r is a complete lattice and that the restriction of t to l r is an infinitely distributive t norm on l r when t is an infinitely distributive t norm on l and 0 is a t prime we present infinitely distributive t norms on a complete sublattice l and study their properties

local image features resulting from 3 dimensional geometric features illumination and movement i we study images of smooth or piecewise smooth objects illuminated by a single light source with only background illumination from other sources the objects may have geometric features f namely surface markings boundary edges creases and corners and shade features s namely shade curves and cast shadow curves we determine the local stable interactions between these and apparent contours c for the various configurations of f s c and we concisely summarize them using an alphabet of local curve configurations we further determine the generic transitions for the configurations resulting from viewer movement these classifications are obtained using the methods of singularity theory which allows us to ensure that our lists are complete in some cases correcting earlier attempts at similar classifications