This is entirely dependent on the program. My undergrad had few set-theoretic math classes. Sure we had to take discrete math and combinatorics, but this kind of notation was lacking. I learned it by way of double-majoring in mathematics.
Conversely, my master's program pretty much assumed you were comfortable with set theory. CS103 is a freshman/sophomore level class at Stanford and is a prerequisite/foundational course for the master's degree. I was out for five years before returning for my master's. It is 100% true that programming skills are more useful in industry, and re-learning the mathematics was the hardest part of returning to school after being out for five years.
With that said, machine learning is eating the world, and it requires a very good understanding of the underlying mathematics.
Conversely, my master's program pretty much assumed you were comfortable with set theory. CS103 is a freshman/sophomore level class at Stanford and is a prerequisite/foundational course for the master's degree. I was out for five years before returning for my master's. It is 100% true that programming skills are more useful in industry, and re-learning the mathematics was the hardest part of returning to school after being out for five years.
With that said, machine learning is eating the world, and it requires a very good understanding of the underlying mathematics.