To provide a general-purpose, practical and high-accuracy classifier having a small number of learning parameters, and allowing application of supervised learning as a lower learning machine.

Training data are stored. Unlabeled data and test data are stored. The supervised learning is performed by the training data. A gradient is stored. The training data, the unlabeled data, and the test data are combined, and the supervised learning is repeatedly performed. A learned discriminant function is stored. A label of the test data is predicted by use of the discriminant function.