I am shocked by the review above, which is mean and ridiculous for abusing a hard-working professor. Firstly, Professor Josz has prepared this course industriously. He made the slides from the scratch, not borrowing others. Besides, he kept recording the classes for us to review, which was not required by the department. In addition, once I noticed that the time of the recorded videos was in the afternoon, demonstrating that he was sacrificing his break time to make the videos more understandable for the sake of our digestion. All the facts can certify that Professor Josz has paid tremendous efforts on this course.
Other evidence also show that he lived up to his responsibilities. He would extend the class to shed light on complicated and abstruse ideas of optimization like max-flow min-cut theorem. In his office hour, if you have questions for him, he would answer patiently and logically, even missing the lunch time. All my statements are based on facts, not mere adjectives or abstract nouns.
Admittedly, there is still something needs to be improved. I think the proof should be preprinted and the emphasis should be on the explanation of the proof, not writting. Also, the link between assignments and classes should be strengthen. However, these cannot serve as excuses for someone to abuse a professor with such a harsh and dirty word.