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Sparsity and information processing

Recently, many information processing methods utilizing the sparsity of the information source is studies. We have reported some results on this line of research. Here we pick up two results from our own works. One is an image reconstruction method …

Channel capacity and achievable rates of peak power limited AWGNC, and their applications to adaptive modulation and coding

The channel conditions vary over time in wireless communications. In order to transmit information efficiently, digital wireless communication systems choose the modulation scheme and coding adaptively. This framework is called the adaptive …

Compton camera imaging

The goal of the Compton camera imaging is to visualize the gamma-ray intensity map. Here, we focus on the case where the gamma-ray sources are sufficiently far from the camera and propose a new reconstruction method for the Compton camera imaging. …

Optimization of probability measure and its applications in information theory

Since Shannon's seminal work, channel capacity has been a fundamental quantity in information thoery. The general definition is formulated as an optimization problem of a probability measure under some moment constraints. Similarly, the definition of …

Rate-distortion function for gamma sources under absolute-log distortion measure

We evaluate the rate-distortion function for the i.i.d. gamma sources with respect to the absolute-log distortion measure. The logarithmic transformation reduces this rate-distortion problem to that under the absolute distortion measure. Extending …

Convex formulation for nonparametric estimation of mixing distribution

We discuss a nonparametric estimation method of the mixing distribution in mixture models. We propose an objective function with one parameter, where its minimization becomes the maximum likelihood estimation or the kernel vector quantization in …

Sparse Phase Retrieval

Motor planning as an optimization of command representation

A fundamental problem in the field of motor neuroscience is to understand how our brain generates appropriate motor commands for precise movements effortlessly. The problem seems difficult since there are infinitely many possible trajectories and our …

Capacity of a single neuron channel

The information transfer through a single neuron is a fundamental information processing in the brain and computing the information channel capacity is important to understand the information processing in the brain. In this work, we discuss the …

A game theoretical analysis of combining classifiers for multi-class classification problems

Combining binary classifiers for multi-class classification problems has been very popular after the invention of SVM and ada-boost, which are known to be very effective for binary classification. In this pater, we analyze theoretically the ECOC …