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Learning Recursive Functions from Approximations
, 1995
"... Investigated is algorithmic learning, in the limit, of correct programs for recursive functions f from both input/output examples of f and several interesting varieties of approximate additional (algorithmic) information about f . Specifically considered, as such approximate additional informatio ..."
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Cited by 17 (7 self)
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Investigated is algorithmic learning, in the limit, of correct programs for recursive functions f from both input/output examples of f and several interesting varieties of approximate additional (algorithmic) information about f . Specifically considered, as such approximate additional information about f , are Rose's frequency computations for f and several natural generalizations from the literature, each generalization involving programs for restricted trees of recursive functions which have f as a branch. Considered as the types of trees are those with bounded variation, bounded width, and bounded rank. For the case of learning final correct programs for recursive functions, EX learning, where the additional information involves frequency computations, an insightful and interestingly complex combinatorial characterization of learning power is presented as a function of the frequency parameters. For EX learning (as well as for BClearning, where a final sequence of cor...
Robust Learning Aided by Context
 In Proceedings of the Eleventh Annual Conference on Computational Learning Theory
, 1998
"... Empirical studies of multitask learning provide some evidence that the performance of a learning system on its intended targets improves by presenting to the learning system related tasks, also called contexts, as additional input. Angluin, Gasarch, and Smith, as well as Kinber, Smith, Velauthapilla ..."
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Cited by 10 (6 self)
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Empirical studies of multitask learning provide some evidence that the performance of a learning system on its intended targets improves by presenting to the learning system related tasks, also called contexts, as additional input. Angluin, Gasarch, and Smith, as well as Kinber, Smith, Velauthapillai, and Wiehagen have provided mathematical justification for this phenomenon in the inductive inference framework. However, their proofs rely heavily on selfreferential coding tricks, that is, they directly code the solution of the learning problem into the context. Fulk has shown that for the Ex and Bcanomaly hierarchies, such results, which rely on selfreferential coding tricks, may not hold robustly. In this work we analyze robust versions of learning aided by context and show that  in contrast to Fulk's result above  the robust versions of This work was carried out while J. Case, S. Jain, M. Ott, and F. Stephan were visiting the School of Computer Science and Engineering at ...
Robust Behaviourally Correct Learning
 Information and Computation
, 1998
"... Intuitively, a class of functions is robustly learnable if not only the class itself, but also all of the transformations of the class under natural transformations (such as via general recursive operators) are learnable. Fulk [Ful90] showed the existence of a nontrivial class which is robustly lea ..."
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Cited by 4 (2 self)
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Intuitively, a class of functions is robustly learnable if not only the class itself, but also all of the transformations of the class under natural transformations (such as via general recursive operators) are learnable. Fulk [Ful90] showed the existence of a nontrivial class which is robustly learnable under the criterion Ex. However, several of the hierarchies (such as the anomaly hierarchies for Ex and Bc) do not stand robustly. Fulk left open the question about whether Bc and Ex can be robustly separated. In this paper we resolve this question positively. 1
Machine induction without revolutionary changes in hypothesis size
 Information and Computation
, 1996
"... This paper provides a beginning study of the effects on inductive inference of paradigm shifts whose absence is approximately modeled by various formal approaches to forbidding large changes in the size of programs conjectured. One approach, called severely parsimonious, requires all the programs co ..."
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Cited by 3 (2 self)
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This paper provides a beginning study of the effects on inductive inference of paradigm shifts whose absence is approximately modeled by various formal approaches to forbidding large changes in the size of programs conjectured. One approach, called severely parsimonious, requires all the programs conjectured on the way to success to be nearly (i.e., within a recursive function of) minimal size. It is shown that this very conservative constraint allows learning infinite classes of functions, but not infinite r.e. classes of functions. Another approach, called nonrevolutionary, requires all conjectures to be nearly the same size as one another. This quite conservative constraint is, nonetheless, shown to permit learning some infinite r.e. classes of functions. Allowing up to one extra bounded size mind change towards a final program learned certainly doesnâ€™t appear revolutionary. However, somewhat surprisingly for scientific (inductive) inference, it is shown that there are classes learnable with the nonrevolutionary constraint (respectively, with severe parsimony), up to (i + 1) mind changes, and no anomalies, which classes cannot be learned with no size constraint, an unbounded, finite number of anomalies in the final program, but with no more than i mind changes. Hence, in some cases, the possibility of one extra mind change is considerably more liberating than removal of very conservative size shift constraints. The proofs of these results are also combinatorially interesting. 1
On Duality in Learning and the Selection of Learning Teams
 Information and Computation
, 1996
"... Previous work in inductive inference dealt mostly with finding one or several machines (IIMs) that successfully learn a collection of functions. Herein we start with a class of functions and consider the learner set of all IIMs that are successful at learning the given class. Applying this perspe ..."
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Cited by 3 (2 self)
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Previous work in inductive inference dealt mostly with finding one or several machines (IIMs) that successfully learn a collection of functions. Herein we start with a class of functions and consider the learner set of all IIMs that are successful at learning the given class. Applying this perspective to the case of team inference leads to the notion of diversification for a class of functions. This enables us to distinguish between several flavors of IIMs all of which must be represented in a team learning the given class. 2 1 Introduction All current theoretical approaches to machine learning tend to focus on a particular machine or a collection of machines and then find the class of concepts which can be learned by these machines under certain constraints defining a criterion of successful learning [AS83, OSW86]. In this paper we investigate the dual problem: Given some set of concepts, which algorithms can learn all those concepts? From [AGS89] we know that in the theory ...
Learning From Context Without CodingTricks
"... Empirical studies of multitask learning provide some evidence that the performance of a learning system on its intended targets improves by presenting to the learning system additional related tasks, also called contexts, as additional input. Angluin, Gasarch, and Smith, as well as Kinber, Smith, Ve ..."
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Empirical studies of multitask learning provide some evidence that the performance of a learning system on its intended targets improves by presenting to the learning system additional related tasks, also called contexts, as additional input. Angluin, Gasarch, and Smith, as well as Kinber, Smith, Velauthapillai, and Wiehagen have provided mathematical justification for this phenomenon in the inductive inference framework. However, their proofs rely heavily on selfreferential coding tricks, that is, they directly code the solution of the learning problem into the context. In this work we prove, in the inductive inference setting, that multitask learning is extremely powerful even without using obvious coding tricks. Coding tricks are avoided in the powerful sense of Fulk's notion of robust learning. Also, studied is the difficulty of the functional dependence between the intended target tasks and useful associated contexts. Department of CIS, University of Delaware, Newark, DE 19716,...