Showing papers on "Tree (data structure) published in 1970"
TL;DR: In this paper, a methodology is developed by which exact and detailed probabilistic information is obtained for any fault tree, which is believed to be a major advancement in reliability and safety analysis and is expected to have far-reaching ramifications.
266 citations
TL;DR: A procedure is proposed which is a generalization of minimal storage tree sorting and which has the following three properties: there is a significant improvement in the expected number of comparisons required to sort the input sequence, the procedure is statistically insensitive to bias in theinput sequence, and the expected numbers of comparisons approaches the information-theoretic lower bound on the number of compared required.
Abstract: The methods currently in use and previously proposed for the choice of a root in minimal storage tree sorting are in reality methods for making inefficient statistical estimates of the median of the sequence to be sorted. By making efficient use of the information in a random sample chosen during input of the sequence to be sorted, significant improvements over ordinary minimal storage tree sorting can be made.A procedure is proposed which is a generalization of minimal storage tree sorting and which has the following three properties: (a) There is a significant improvement (over ordinary minimal storage tree sorting) in the expected number of comparisons required to sort the input sequence. (b) The procedure is statistically insensitive to bias in the input sequence. (c) The expected number of comparisons required by the procedure approaches (slowly) the information-theoretic lower bound on the number of comparisons required. The procedure is, therefore, “asymptotically optimal.”
179 citations
TL;DR: In this article, the authors present observations of Hummingbird territorial interactions at a tropical flowering tree, Genipa americana, of the Rubiaceae, in two successive years.
Abstract: INTERSPECIFIC competition is generally a subtle phenomenon that must often be inferred rather than observed directly. Hummingbirds are unusual among birds in that competition for food is frequently demonstrated by overt aggression between individuals of different species. Males of many species of hummingbirds defend territories at feeding sites against all other hummingbirds, regardless of species or sex. Such feeding territories typically center about flowering plants, whether these yield insects, nectar, or both. A territory is defined as a spatially limited site in which the resident restricts use of environmental resources (here, nectar) to satisfy its own requirements (Wolf, 1969). The distribution of flowers in time and space can be expected to influence the outcome of intraand interspecific competition among hummingbirds. The density and richness of food sources may affect the minimum territory size required to control sufficient energy resources. The actual extent of a defended area probably also depends on such factors as foliage density and the availability of display perches, which affect the bird's ability to advertise, scan, and defend its territory. Both the length of the blooming season and the availability of alternative food sources will influence the duration and rigidity of the territorial system (Wolf, 19'70). Interspecific territoriality may result in the exclusion of weaker or less aggressive species from the food source and/or in a partition of the feeding area between two or more competing species. Instances of exclusion in hummingbirds are numerous in the literature (e.g. Bent, 1940; Pitelka, 1942; Skutch, 1961); the usual situation appears to be for larger species to drive out smaller ones. Partitioning of a feeding area may be viewed as a dynamic equilibrium that varies with the relative numbers and pugnacity of the hummingbird species concerned. Small interspecific differences in foraging habits could contribute to or reinforce such a partitioning, especially if the flowering area is heterogeneous. In particular, different feeding height preferences could lead to a stable stratification of hummingbird species in flowering trees. This paper presents observations of territorial interactions of the hummingbirds Amazilia rutila, A. saucerottei, and Phaeochroa cuvierii at a tropical flowering tree, Genipa americana, of the Rubiaceae. They were made in 2 successive years at the same locality, and in large part at the
139 citations
TL;DR: A transformational derivation of a sentence is a sequence of labeled phrase structure trees that represent that syntactic structure relevant to the way in which the sentence is pronounced.
Abstract: A transformational derivationof a sentence is a sequence of labeled phrase structure trees. The last tree in the sequence represents the surface structureof the sentence. The first tree represents the deep structureof the sentence.1Each later tree is derived from its predecessor via the application of exactly one transformational rule. The surface structure tree represents that syntactic structure relevant to the way in which the sentence is pronounced. It will be assumed here that the deep structure tree is a full semantic representation of the sentence.2
80 citations
TL;DR: Two types of random trees, “static” and “growing,” are studied and exact formulas for the expected number of nodes of degree i are derived in each case.
Abstract: Two types of random trees, “static” and “growing,” are studied. The “growing” type of trees is constructed with an ordering bias imposed on its population of N nodes. Exact formulas for the expected number of nodes of degree i are derived in each case. Asymptotic behavior of such formulas is determined for large values of N.
69 citations
65 citations
Patent•
26 Jan 1970
TL;DR: Improved structure for an artificial tree such as a Christmas tree having a hollow trunk with hollow sleeved limbs pivotally mounted on the trunk at decreasing distances toward the tree top for folding of the structure into minimized volume as discussed by the authors.
Abstract: Improved structure for an artificial tree such as a Christmas tree having a hollow trunk with hollow sleeved limbs pivotally mounted on the trunk at decreasing distances therefrom toward the tree top for folding of the structure into minimized volume. Electrical wiring extending from limbs through the tree trunk provides an integral lighting system and adds structural rigidity while limb covers provide maximized realistic appearance.
55 citations
TL;DR: In this paper, the authors investigated the effect of direct instruction on the ability to handle permutations and arrangements, as an example of a problem at the level of formal operations, and found that these subjective estimates improved with age, with a threshold (or marked improvement) at age 12, though there was serious underestimation at all ages.
Abstract: Summary. The aim of the study was to investigate the effect of direct instruction on the ability to handle permutations and arrangements, as an example of a problem at the level of formal operations. 60 Bucharest school children, 20 aged 10 years, 20 aged 12 and 20 aged 14, tested individually, were first asked to estimate the number of possible permutations with 3, 4 and 5 objects. Results showed that these subjective estimates improved with age, with a threshold (or marked improvement) at age 12, though there was serious underestimating at all ages. A step-by-step teaching strategy using generative ‘tree diagrams’ was then used. Even the 10-year-olds learned the use of the tree diagrams and the appropriate procedures for permutations and arrangements.
51 citations
Patent•
06 Nov 1970
TL;DR: A collapsible artificial tree construction particularly adapted for Christmas decoration in which simulated branches are freely foldable substantially parallel to the simulated tree trunk in one direction and freely pivot to an unfolded laterally extending direction when the artificial tree is to be erected and used as discussed by the authors.
Abstract: A collapsible artificial tree construction particularly adapted for Christmas decoration in which simulated branches are freely foldable substantially parallel to the simulated tree trunk in one direction and freely pivot to an unfolded laterally extending direction when the artificial tree is to be erected and used, and in which the branches freely gravitate to an unfolded condition whereby insertion of the tree trunk into a tubular container automatically folds the branches upwardly and along the trunk, and removal of the tree from a tubular container results in the branches being automatically unfolded. Also, the branches may be folded against the trunk by gravity by turning the tree upside down.
Patent•
30 Mar 1970
TL;DR: The tree stand is collapsible for storage, and includes means to positively latch the tree shaft receptacle in adjusted positions of tilt, thereby minimizing the risk of accidental release of the receptacle and possible overturning of the assembly.
Abstract: The tree stand is collapsible for storage, and includes means to positively latch the tree shaft receptacle in adjusted positions of tilt, thereby minimizing the risk of accidental release of the receptacle and possible overturning of the assembly.
Patent•
19 Oct 1970
TL;DR: In this paper, a tree covering including a tinsel garland attached to backing strips in a pre-designed pattern is adapted to be draped over a tree, such as a Christmas tree, for ornamentation purposes.
Abstract: A decorative tree covering including a tinsel garland attached to backing strips in a pre-designed pattern. The tall covering is adapted to be draped, in tent-like fashion, over a tree, such as a Christmas tree, for ornamentation purposes. An alternate embodiment utilizes a web network for supporting the garland; the tree is further adorned with bows, etc., attached to the network.
Patent•
16 Sep 1970
TL;DR: In this article, a timber-felling tree-pulling apparatus is described, which draws a tree up with its roots, the tree being first pulled out of the ground in a vertical direction and thereafter prized at an increasing angle.
Abstract: A timber-felling apparatus which draws a tree up with its roots the tree being first pulled out of the ground in a vertical direction and thereafter prized at an increasing angle thereto. The apparatus has means to cut off all or a portion of the roots attached to the tree during the pulling out thereof or after the tree has been pulled out.
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01 Dec 1970
TL;DR: Four example problems illustrate the construction of the tree, combination of probabilities, and use of Boolean algebra and the description of simulation techniques provides a bridge from simple example problems to actual complex systems.
Abstract: : The paper is intended to give the reader a basic background in the system safety technique of fault tree analysis and related concepts Four example problems illustrate the construction of the tree, combination of probabilities, and use of Boolean algebra The description of simulation techniques provides a bridge from simple example problems to actual complex systems (Author)
Journal Article•
Patent•
24 Apr 1970
TL;DR: In this article, a feller buncher is used to support the weight of a tree and apply a force against the lower end of a severed tree so that it will topple into an elongated collecting trough.
Abstract: A feller buncher apparatus including in combination a cutter device, an elongated collected trough for severed trees, means to support the weight of a tree, and means to apply a force against the lower end of a severed tree so that it will topple into said elongated collecting trough.