This video presents the Product Construction for DFA's, which allows us to show that the union or intersection of two regular sets is regular by, in essence, running two DFA's at the same time. It can move quickly, so please pause and rewind as necessary!
Thanks to Amy Briggs (Middlebury College) for introducing me to this material, as well as Dexter Kozen (Cornell University) for the text that we used and Wayne Goddard (Clemson University) for the additional perspective provided by his text.
