Rough Set Data Analysis: A Round to Noninvasive Knowledge Discovery  
This is not the first book on rough set analysis and certainly not the first book on knowledge discovery algorithms, but it is the first attempt to do this in a noninvasive way. In this book the authors present an overview of the work they have done in the past seven years on the foundations and details of data analysis. 
A First Course in Linear Algebra  
A First Course in Linear Algebra is an introductory textbook aimed at collegelevel sophomores and juniors. PDF versions are available now, and an online version is inprogress. 
A Problem Course in Mathematical Logic  
A Problem Course in Mathematical Logic is intended to serve as the text for an introduction to mathematical logic for undergraduates with some mathematical sophistication. It supplies definitions, statements of results, and problems, along with some explanations, examples, and hints. 
Complex Analysis  
This is free a textbook for an introductory course in complex analysis. It can be downloaded in pdf format free of charge. 
Elementary Number Theory  
This is a free textbook about prime numbers, congruences, basic publickey cryptography, quadratic reciprocity, continued fractions, elliptic curves, and number theory algorithms. 
