We define a rich model to be one which contains a proper elementary substructure isomorphic to itself. Existence, non-structure, and categoricity theorems for rich models are proved. We show that a countable theory with few rich models is categorical in Ki. We also consider a stronger notion of richness, and in discussing it prove: "If T is an unstable theory, then for any saturated model M of ...

There are several different methods to make an efficient strategy for steganalysis of digital images. A very powerful method in this area is rich model consisting of a large number of diverse sub-models in both spatial and transform domain that should be utilized. However, the extraction of a various types of features from an image is so time consuming in some steps, especially for training pha...

In this paper, we propose a regression framework for steganalysis of digital images that utilizes the recently proposed rich models – high-dimensional statistical image descriptors that have been shown to substantially improve classical (binary) steganalysis. Our proposed system is based on gradient boosting and utilizes a steganalysis-specific variant of regression trees as base learners. The ...