Why Gabor Frames? Two Fundamental Measures of Coherence and Their Role in Model Selection
The problem of model selection arises in a number of contexts, such as subset selection in linear regression, estimation of structures in graphical models, and signal denoising. This paper studies non-asymptotic model selection for the general case of arbitrary (random or deterministic) design matrices and arbitrary nonzero entries of the signal. In this regard, it generalizes the notion of incoherence in the existing literature on model selection and introduces two fundamental measures of coherence - termed as the worst-case coherence and the average coherence - among the columns of a design matrix.