The logic of message-passing

Message-passing is a key ingredient of concurrent programming. The purpose of this paper is to describe the equivalence between the proof theory, the categorical semantics, and term calculus of message-passing. In order to achieve this we introduce the categorical notion of a linear actegory and the related polycategorical notion of a poly-actegory. Not surprisingly the notation used for the term calculus borrows heavily from the (synchronous) π-calculus. The cut-elimination procedure for the system provides an operational semantics.     

一种多值返回的层次化分类方法

随着Internet上信息量的飞速增长,成千上万的网上文档需要分类以方便用户的测览和获取。因此文档的自动分类工作已经越来越受到重视,一些相应的分类方法也应运而生。但其中很少有涉及到“层次化”的分类领域,且绝大多数方法仅仅返回单个分类结果。文中,我们提出了一种新的文档自动分类方法：MRHC(Multicategory-Returned Algorithm for Hierarchical aassification)。该方法着眼于屡次化的分类技术,并在适当的情况下为文档返回多个分类结果。该方法中结合了特征削减和增量学习技术以便提高分类性能。最后,为了更加准确、客观的评价分类结果,提出了一种新的评估方法：LEP(Length-of-Error-Path)。实验结果表明,提出的分类方法响应时间短,分类准确度高,具有较强的实用性。     

On learning multicategory classification with sample queries

Consider the pattern recognition problem of learning multicategory classification from a labeled sample, for instance, the problem of learning character recognition where a category corresponds to an alphanumeric letter. The classical theory of pattern recognition assumes labeled examples appear according to the unknown underlying pattern-class conditional probability distributions where the pattern classes are picked randomly according to their a priori probabilities. In this paper we pose the following question: Can the learning accuracy be improved if labeled examples are independently randomly drawn according to the underlying class conditional probability distributions but the pattern classes are chosen not necessarily according to their a priori probabilities? We answer this in the affirmative by showing that there exists a tuning of the sub-sample proportions which minimizes a loss criterion. The tuning is relative to the intrinsic complexity of the Bayes-classifier. As this complexity depends on the underlying probability distributions which are assumed to be unknown, we provide an algorithm which learns the proportions in an on-line manner utilizing sample querying which asymptotically minimizes the criterion. In practice, this algorithm may be used to boost the performance of existing learning classification algorithms by apportioning better sub-sample proportions.     

A Multicategory Kernel Distance Weighted Discrimination Method for Multiclass Classification

Abstract

Distance weighted discrimination (DWD) is an interesting large margin classifier that has been shown to enjoy nice properties and empirical successes. The original DWD only handles binary classification with a linear classification boundary. Multiclass classification problems naturally appear in various fields, such as speech recognition, satellite imagery classification, and self-driving vehicles, to name a few. For such complex classification problems, it is desirable to have a flexible multicategory kernel extension of the binary DWD when the optimal decision boundary is highly nonlinear. To this end, we propose a new multicategory kernel DWD, that is, defined as a margin-vector optimization problem in a reproducing kernel Hilbert space. This formulation is shown to enjoy Fisher consistency. We develop an accelerated projected gradient descent algorithm to fit the multicategory kernel DWD. Simulations and benchmark data applications are used to demonstrate the highly competitive performance of our method, as compared with some popular state-of-the-art multiclass classifiers.