"It is this author’s personal belief that the most important part of machine learning is the mathematical foundation, followed closely by efficiency in implementation details."<p>An introductory ML material in my opinion can be less mathematically rigorous. Emphasis can be on intuitive understanding of principles of various techniques, the strengths and weaknesses of each and the application of ML techniques to various simplified problems for practice. It is easy to get lost in too much Math and loose sight of real world problem solving.