61,844 research outputs found
Near-Optimal Online Multiselection in Internal and External Memory
We introduce an online version of the multiselection problem, in which q
selection queries are requested on an unsorted array of n elements. We provide
the first online algorithm that is 1-competitive with Kaligosi et al. [ICALP
2005] in terms of comparison complexity. Our algorithm also supports online
search queries efficiently.
We then extend our algorithm to the dynamic setting, while retaining online
functionality, by supporting arbitrary insertions and deletions on the array.
Assuming that the insertion of an element is immediately preceded by a search
for that element, we show that our dynamic online algorithm performs an optimal
number of comparisons, up to lower order terms and an additive O(n) term.
For the external memory model, we describe the first online multiselection
algorithm that is O(1)-competitive. This result improves upon the work of
Sibeyn [Journal of Algorithms 2006] when q > m, where m is the number of blocks
that can be stored in main memory. We also extend it to support searches,
insertions, and deletions of elements efficiently
Elements of Design for Containers and Solutions in the LinBox Library
We describe in this paper new design techniques used in the \cpp exact linear
algebra library \linbox, intended to make the library safer and easier to use,
while keeping it generic and efficient. First, we review the new simplified
structure for containers, based on our \emph{founding scope allocation} model.
We explain design choices and their impact on coding: unification of our matrix
classes, clearer model for matrices and submatrices, \etc Then we present a
variation of the \emph{strategy} design pattern that is comprised of a
controller--plugin system: the controller (solution) chooses among plug-ins
(algorithms) that always call back the controllers for subtasks. We give
examples using the solution \mul. Finally we present a benchmark architecture
that serves two purposes: Providing the user with easier ways to produce
graphs; Creating a framework for automatically tuning the library and
supporting regression testing.Comment: 8 pages, 4th International Congress on Mathematical Software, Seoul :
Korea, Republic Of (2014
The fourth dimension: A motoric perspective on the anxiety–performance relationship
This article focuses on raising concern that anxiety–performance relationship theory has insufficiently catered for motoric issues during, primarily, closed and self-paced skill execution (e.g., long jump and javelin throw). Following a review of current theory, we address the under-consideration of motoric issues by extending the three-dimensional model put forward by Cheng, Hardy, and Markland (2009) (‘Toward a three-dimensional conceptualization of performance anxiety: Rationale and initial measurement development, Psychology of Sport and Exercise, 10, 271–278). This fourth dimension, termed skill establishment, comprises the level and consistency of movement automaticity together with a performer's confidence in this specific process, as providing a degree of robustness against negative anxiety effects. To exemplify this motoric influence, we then offer insight regarding current theories’ misrepresentation that a self-focus of attention toward an already well-learned skill always leads to a negative performance effect. In doing so, we draw upon applied literature to distinguish between positive and negative self-foci and suggest that on what and how a performer directs their attention is crucial to the interaction with skill establishment and, therefore, performance. Finally, implications for skill acquisition research are provided. Accordingly, we suggest a positive potential flow from applied/translational to fundamental/theory-generating research in sport which can serve to freshen and usefully redirect investigation into this long-considered but still insufficiently understood concept
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