Showing papers on "Tree (data structure) published in 1977"

Additive similarity trees

Abstract: Similarity data can be represented by additive trees. In this model, objects are represented by the external nodes of a tree, and the dissimilarity between objects is the length of the path joining them. The additive tree is less restrictive than the ultrametric tree, commonly known as the hierarchical clustering scheme. The two representations are characterized and compared. A computer program, ADDTREE, for the construction of additive trees is described and applied to several sets of data. A comparison of these results to the results of multidimensional scaling illustrates some empirical and theoretical advantages of tree representations over spatial representations of proximity data.

A new representation for linear lists

Abstract: We present a new data structure for maintaining a set of records in a linear list according to their key values. This data structure has the property that we can keep a number of fingers at points of interest in the key space (e.g., the beginning or the end of the list), so that access and modification in the neighborhood of a finger is very efficient. In the Section 2 we discuss the general structure of our B-tree. Since we propose to search the tree from a leaf upwards, additional links need to be introduced. In Section 3 we show how to obtain our result for the case of one finger. A key idea is the construction of a number representation behaving as described above, which we can use to model the propagation of modifications in the B-tree along the finger path. In Section 4 we generalize the structure so that several fingers in the key space can be maintained, with the advantage that access is cheap in the neighborhood of each finger. Finally in Section 5 we present some implementation notes and applications, mostly to sorting.

The navigation system of the JPL robot

Abstract: The control structure of the JPL research robot and the operations of the navigation subsystem are discussed The robot functions as a network of interacting concurrent processes distributed among several computers and coordinated by a central executive The results of scene analysis are used to create a segmented terrain model in which surface regions are classified by traversibility The model is used by a path-planning algorithm, PATH, which uses tree search methods to find the optimal path to a goal In PATH, the search space is defined dynamically as a consequence of node testing Maze-solving and the use of an associative data base for context-dependent node generation are also discussed Execution of a planned path is accomplished by a feedback guidance process with automatic error recovery

An Analysis of a Good Algorithm for the Subtree Problem

Abstract: A good algorithm is analyzed for deciding if one tree is a subtree of another tree. If both trees are rooted, the smaller tree has n vertices and the larger has m vertices; then the total number of computations is $O(nm^{1.5})$ or better, depending on how good an algorithm one has for a maximal matching in a bipartite graph.

The ties that bind

Abstract: The roots of trees such as the Douglas fir or birch can be colonized by many fungal species, toform so-called ‘ectomycorhizza’ These symbiotic fungal networks can extend from tree to tree,and a new study shows that considerable amounts of carbon can betransferred between trees --in either direction -- through these networks Moreover, if one tree is in the shade, it willreceive increased amounts of carbon

On the Mechanism of Tree Initiation

Abstract: Although the dc-tree-initiation voltage at a needle electrode in a plastic is very high, a tree can be formed by grounding the needle after charging it with a much lower dc voltage than the tree-initiation voltage. The tree formed by grounding will be called "a grounding tree". Since the formation of a tree under ac voltages is considered to be due to the repetition of charging and discharing, some relationship may exist between the ac tree and the grounding tree. The tree-initiation observed with a voltage composed of dc and ac shows that it is caused by a nearly constant value of the ac component, irrespective of the magnitude of the dc component. This also indicates that the mechanism of the intiation of an ac tree and that of a grounding tree are similar. An explanation is also given as to why the tree shape is branch-like or bush-like with ac voltages.

Analysis of the Multiple-Attribute-Tree Data-Base Organization

Abstract: The multiple-attribute-tree (MAT) data-base organization is modeled and analyzed. Average retrieval time per query is obtained using a statistical estimation procedure and computationally efficient cost equations are presented. These cost equations are validated using a small experimental data base. Several real-life and generated data bases are used to demonstrate the effectiveness of the multiple-attribute-tree organization in reducing the expected retrieval time per query over conventional methods.

Diagnosis of Faults in Linear Tree Networks

Abstract: The problem of fault detection and location in tree networks of two input EXCLUSIVE-OR (EOR) gates is considered. The fault model assumes that an EOR gate can change to any other function of its two inputs except the equivalence function. An efficient procedure for single fault location is presented. In the worst case the number of tests necessary to locate single faults is bounded by a linear function of the number of input variables. Constructive upper bounds are obtained for the number of tests to detect multiple faults. Optimality of these bounds is argued and extension of results to other types of networks is considered.

Correcting human error in alphanumeric terminal input

Abstract: An automatic method for correcting spelling and typing errors from teletypewriter keyboard input is proposed. The computerized correcting process is presented as a heuristic tree search. The correct spellings are stored character-by-character in a psuedo-binary tree. The search examines a small subset of the database (selected branches of the tree) while checking for insertion, substitution, deletion and transposition errors. The correction procedure utilizes the inherent redundancy of natural language. Multiple errors can be handled if at least two correct characters appear between errors. Test results indicate that this approach has the highest error correction accuracy to date.

Social stress in tree-shrews: Problems, results, and goals

Abstract: \"S t ress\" is an ancient and familiar English noun, but its meaning in current usage is not at all widely understood. The term has long been in use in mechanics, denoting a force that acts on an object and brings about a transient or permanent change in its shape; this change is called \"s t ra in\" . It is in just this sense that \"s t ress\" is usually used in psychology and sociology. In 1915 Cannon introduced the term into physiology with a corresponding meaning: stress is a stimulus that acts on an organism so as to \" s t r a in\" its ability to resist. A contrasting definition was given by the physiologist Selye, who brought the notion of stress into general populari ty; he called the stimulus acting on an organism the \"s t ressor\" and reserved the term \"s t ress\" for the change in the state of the individual thus produced. To every stressor (whether physical or psychological in nature), according to Selye, the organism adjusts by means of a great number of nervous and hormonal changes which act to increase the resistance of the organism; together, these are termed the \"Genera l Adaptat ion Syndrome (GAS)\". Selye regarded the reaction of an organism to such an imposed stimulus as particularly characterized by a more or less marked ac t iva t ion-cor responding to the intensity of the s t r e s s o r o f the hypophyseal-adrenocortical axis; the term \"s t ress\" thus is usually used as a synonym for \"adrenal-cortex act ivat ion\" (for a survey see Selye, 1950). Whereas physiological research on stress was originally the exclusive province of medicine and psychology (see summaries in, e.g., Lazarus, 1966), stress responses have also been of interest to zoologists for some years, because they can contribute to an understanding of self-regulation in mammal ian populations. According to a concept proposed in 1950 by Christian, increasing population density leads to changes in social relationships which result in a corresponding increase in stress, to which the animals adapt with hormonal changes. These adaptat ion reactions are primarily characterized by increased activation of the

If a tree had a knee, where would it be? Children's performance on simple spatial metaphors

Abstract: This research is concerned with the development of metaphorical ability, conceived of as the ability to preserve conceptual relationships across changes in actual content. This view of metaphorical ability does not distinguish between analogy, metaphor and simile, but focuses rather on what I believe to be their common core. I define a metaphor or analogy as a mapping from one semantic region (the domain of origin) to another (the range of application) which conveys that certain semantic or conceptual relationships present in the domain are present in the range also. Further details of this model and of Experiment 1 are reported in Gentner (in press). The development of metaphorical ability is not well understood. The spontaneous speech of preschool children is full of seemingly metaphorical remarks. For example, a two-year-old says "Oh Mommie! How balloonie your legs are!" or (when undressed) "I' m barefoot all-over." (Chukovsky, 1968). It appears that not all these extensions arise from errors in the child' s word meanings (cf Thomson & Chapman, 1975). However, in experimental tasks designed to measure metaphorical ability preschool children acquit themselves rather poorly. Typical tasks used are interpretation of metaphors, such as "Can a person be soft? (Asch and Nerlove, 1960); or choosing among possible metaphorical and nonmetaphorical completions for completing sentences such as "Look at that boy standing over there. He looks as gigantic Performance on these tasks rises fairly steadily with age until adolescence. These results seem to indicate that metaphorical ability develops after the acquisition of basic language skills. The laboratory result that preschool children are poor at metaphor is at odds with the observation that novel comparisons are very common in their spontaneous speech. On closer examination, however, it appears that factors other then metaphorical ability are measured in these studies. One important factor is the children's conceptual knowledge, or lack of knowledge, of the domain from which the metaphor is taken and of the domain in which it is applied. For example, if young children do not know the culturally agreed-upon systems of personality traits and emotional states

Random resistor tree in an applied field

Abstract: The macroscopic conductivity defined by De Gennes is calculated for a Cayley tree of random resistors. The conductivity exponents are t=3 and s=(log). The implications for the dimensionality dependence of the conductivity exponents is discussed.

A study on the pattern method for the decision process in the public system

Abstract: In this paper, I try to apply the PATTERN method(Planning Assistance Through Technical Evaluation of Relevance Number)for the decision process in the public system and attempt to construct a theoretical framework to explain the PATTERN method procedures.In this way, the PATTERN method procedures are to understand the public problem and solve it by three steps as follows.(a)To write the scenario from the public's point of view.(b)To build up the relevance tree from the content of the scenario.(c)To make the quantitative evaluation on the relevance tree.From these steps is developed a theoretical framework to construct the relevance tree from the scenario writing. At the same time, the multistage decision theory is applied to this relevance tree through the quantitative evaluation.This method is obtained by the consensus of the public opinions. Meanwhile, a decision making can be made in the public problem.Finally, this method is also applied to perform a case study of“the Public Problem of the Industrial Waste Treatment Planning”. I made a summary of it and examined its result.

Tree Realizations of Iterative Circuits

Abstract: It is shown how any combinational function that can be described by a flow table—or equivalently—is realizable in iterative form—can be realized in tree form. The propagation delay is then proportional to the logarithm of n, the number of inputs, while the logic complexity is a linear function of n. These results are related to various implementations of high-speed binary adders and a proposed new high-speed adder circuit.

Hinged branch holder

Abstract: A hinge assembly for artificial Christmas trees that allows for the collapse of the tree without danger of the hinge binding or pinching materials in contact with the hinge and which is well suited to fabrication by mass production techniques.

Efficient Construction of Minimal Cut Sets from Fault Trees

Abstract: A formal method and an algorithm are presented to determine minimal cut sets (MCSs) from fault trees. The method is based upon segmenting the tree, constructing MCSs of subtrees and subsequent expanding into the MCS of the original tree. The major advantage of the method is the direct determination of MCSs up to any order required. More particularly, the algorithm DICOMICS allows straightforward analyses for all those cases (large trees, high order cut sets, repeated elements) where present combinatorial and Monte Carlo techniques are not effective. Compared with other structural algorithms now in use, DICOMICS provides a near optimal effective construction of MCSs. Thus, even when there are many redundant cut sets, computer implementations yield a substantial reduction of computing steps and effort. Hand calculation and interactive programming are also possible.

Sportsman's seat

Abstract: A foldable assembly comprising a seat rotatably mounted on a support to which are collapsibly mounted three legs. One of the legs can be secured to a tree. Foothold means are provided on one of the legs. Means are provided also to adjust the length of the legs.

Artificial and mechanical tree

Abstract: An artificial and mechanical tree which includes a pole member and a plurality of vertical, accordion-type limb sections is disclosed. Each of the tree limb sections has the tree limbs attached to a vertically collapsible and expandable tubular member which is concentric with and removably attached in the expanded configuration to the pole member.

Christmas tree holder

Abstract: A stand of a generally hemispheric configuration base. A plurality of clamping legs are provided which are arcuately curved and pass through channels formed in the base. The legs will pass through the respective channels into gripping relationship with the tree trunk when it is inserted into a central containing body in the stand. Thus, the weight of the tree itself serves to locate, hold and place into operation the gripping legs of the combination.

SCIRTSS: A Search System for Sequential Circuit Test Sequences

Abstract: This paper describes SCIRTSS (a sequential circuit test search system). An analytical basis is given for using tree search techniques in determining test sequences for sequential circuits. The basic algorithm for the system of SCIRTSS programs is described and the extent to which the user can influence the search procedure is discussed. Included are the results of the application of SCIRTSS to eight sequential circuits of varying complexity on each one of which it succeeded in finding a fault detection sequence for at least 98 percent of the simple logical faults. This suggests that SCIRTSS can be effective on more complex LSI parts than other automatic test generation methods currently available. Breaking the tree search into two separate search procedures and partitioning circuits when possible into control and data sections are unique features which contribute to SCIRTSS efficiency.

On the Halting of Tree Replacement Systems.

Abstract: : A meta theorem is proved giving sufficient conditions for termination of tree replacement systems. This leads to a new proof methodology for proving termination of optimization techniques. (Author)