Relevance vector machine
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In mathematics, a Relevance Vector Machine (RVM) is a machine learning technique that uses Bayesian inference to obtain parsimonious solutions for regression and probabilistic classification.[1] The RVM has an identical functional form to the support vector machine, but provides probabilistic classification.
It is actually equivalent to a Gaussian process model with covariance function:
where is the kernel function (usually Gaussian),'s as the variances of the prior on the weight vector ,and are the input vectors of the training set.[2]
Compared to that of support vector machines (SVM), the Bayesian formulation of the RVM avoids the set of free parameters of the SVM (that usually require cross-validation-based post-optimizations). However RVMs use an expectation maximization (EM)-like learning method and are therefore at risk of local minima. This is unlike the standard sequential minimal optimization (SMO)-based algorithms employed by SVMs, which are guaranteed to find a global optimum (of the convex problem).
The relevance vector machine is patented in the United States by Microsoft.[3]
See also
- Kernel trick
- Platt scaling: turns an SVM into a probability model
References
- ↑ Tipping, Michael E. (2001). "Sparse Bayesian Learning and the Relevance Vector Machine". Journal of Machine Learning Research 1: 211–244.
- ↑ Candela, Joaquin Quiñonero (2004). "Sparse Probabilistic Linear Models and the RVM". Learning with Uncertainty - Gaussian Processes and Relevance Vector Machines (PDF) (Ph.D.). Technical University of Denmark. Retrieved April 22, 2016.
- ↑ US 6633857, Michael E. Tipping, "Relevance vector machine"
Software
- dlib C++ Library
- The Kernel-Machine Library
- rvmbinary:R package for binary classification
- scikit-rvm
- fast-scikit-rvm , rvm tutorial
External links
- Tipping's webpage on Sparse Bayesian Models and the RVM
- A Tutorial on RVM by Tristan Fletcher
- Applied tutorial on RVM
- Comparison of RVM and SVM