Graph-based methods form a main category of semisupervised
learning, offering flexibility and easy implementation
in many applications. However, the performance of
these methods is often sensitive to the construction of a
neighborhood graph, which is non-trivial for many realworld
problems. In this paper, we propose a novel framework
that builds on learning the graph given labeled and
unlabeled data. The paper has two major contributions.
Firstly, we use a nonparametric algorithm to learn the entire
adjacency matrix of a symmetry-favored k-NN graph,
assuming that the matrix is doubly stochastic. The nonparametric
algorithm makes the constructed graph highly robust
to noisy samples and capable of approximating underlying
submanifolds or clusters. Secondly, to address multi-class
semi-supervised classification, we formulate a constrained
label propagation problem on the learned graph by incorporating
class priors, leading to a simple closed-form solution.
Experimental re...