In empirical cognitive science, for human learning, a semantic or behavioral U-shape occurs when a learnerfirst learns, then unlearns, and, finally, relearns, some target concept. Within the formal framework of Induc...
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In empirical cognitive science, for human learning, a semantic or behavioral U-shape occurs when a learnerfirst learns, then unlearns, and, finally, relearns, some target concept. Within the formal framework of Inductive Inference, for learning from positive data, previous results have shown, for example, that such U-shapes are unnecessary for explanatory learning, but are necessary for behaviorally correct and non-trivial vacillatory learning. Herein we also distinguish between semantic and syntactic U-shapes. We answer a number of open questions in the prior literature as well as provide new results regarding syntactic U-shapes. Importantly for cognitive science, we see more of a previously noticed pattern that, for parameterized learning criteria, beyond very few initial parameter values, U-shapes are necessary forfull learning power. We analyze the necessity of U-shapes in two memory-limited settings. The first setting is Bounded Memory State (BMS) learning, where a learner has an explicitly-bounded state memory, and otherwise only knows its current datum. We show that there are classes learnable with three (or more) memory states that are not learnable non-U-shapedly with any finite number of memory states. This result is surprising, since, for learning with one or two memory states, U-shapes are known to be unnecessary. This solves an open question from the literature. The second setting is that of Memoryless feedback (MLf) learning, where a learner may ask a bounded number of questions about what data has been seen so far, and otherwise only knows its current datum. We show that there is a class learnable memorylessly with a single feedback query such that this class is not learnable non-U-shapedly memorylessly with any finite number offeedback queries. We employ self-learning classes together with the Operatorrecursion Theorem for many of ourresults, but we also introduce two new techniques for obtaining results. The first is for transferring inclusion
We refine the bound on the packing number, originally shown by Haussler, for shallow geometric set systems. Specifically, let V be a finite set system defined over an n-point set X;we view V as a set of indicator vect...
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ISBN:
(纸本)9783939897835
We refine the bound on the packing number, originally shown by Haussler, for shallow geometric set systems. Specifically, let V be a finite set system defined over an n-point set X;we view V as a set of indicator vectors over the n-dimensional unit cube. A δ-separated set of V is a subcollection W, s.t. The Hamming distance between each pair u, v 2 W is greater than δ, where δ > 0 is an integer parameter. The δ-packing number is then defined as the cardinality of the largest δ-separated subcollection of V. Haussler showed an asymptotically tight bound of φ((n/δ)d) on the δ-packing number if V has VC-dimension (or primal shatterdimension) d. We refine this boundfor the scenario where, for any subset, X′ ⊆ X of size m ≤ n andfor any parameter 1 ≤ κ ≤ m, the number of vectors of length at most κ in the restriction of V to X′ is only O(md1kd-d1 ), for a fixed integerd > 0 and a real parameter 1 ≤ d1 ≤ d (this generalizes the standard notion of bounded primal shatterdimension when d1 = d). In this case when V is "κ-shallow" (all vector lengths are at most κ), we show that its δ-packing number is O(nd1kd-d1/δd), matching Haussler s boundfor the special cases where d1 = d or κ = n. We present two proofs, the first is an extension of Haussler s approach, and the second extends the proof of Chazelle, originally presented as a simplification for Haussler s proof.
In recent years a lot of progress has been made in understanding the behavior of evolutionary computation methods for single- and multi-objective problems. Our aim is to analyze the diversity mechanisms that are impli...
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In recent years a lot of progress has been made in understanding the behavior of evolutionary computation methods for single- and multi-objective problems. Our aim is to analyze the diversity mechanisms that are implicitly used in evolutionary algorithmsfor multi-objective problems by rigorous runtime analyses. We show that, even if the population size is small, the runtime can be exponential where corresponding single-objective problems are optimized within polynomial time. To illustrate this behavior we analyze a simple plateau function in a first step and extend ourresult to a class of instances of the well-known SETCOVEr problem.
Ant Colony Optimization (ACO) is a powerful metaheuristic for solving combinatorial optimization problems. With this paper we contribute to the theoretical understanding of this kind of algorithm by investigating the ...
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ISBN:
(纸本)9781450300728
Ant Colony Optimization (ACO) is a powerful metaheuristic for solving combinatorial optimization problems. With this paper we contribute to the theoretical understanding of this kind of algorithm by investigating the classical minimum cut problem. An ACO algorithm similar to the one that was proved successful for the minimum spanning tree problem is studied. Using rigorous runtime analyses we show how the ACO algorithm behaves similarly to Karger and Stein's algorithm for the minimum cut problem as long as the use of pheromone values is limited. Hence optimal solutions are obtained in expected polynomial time. On the other hand, we show that high use of pheromones has a negative effect, and the ACO algorithm may get trapped in local optima resulting in an exponential runtime to obtain an optimal solution. This result indicates that ACO algorithms may be inappropriate forfinding minimum cuts. Copyright 2010 ACM.
determining the precise integrality gap for the subtour LP relaxation of the traveling salesman problem is a significant open question, with little progress made in thirty years in the general case of symmetric costs ...
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We prove that the number of vertices of given degree in random planar maps satisfies a central limit theorem with mean and variance that are asymptotically linear in the number of edges. The proofrelies on an analyti...
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