The discussion focuses on determining whether to use the subset symbol (⊆) or the not a subset symbol (⊄) in various mathematical expressions. The first two expressions are confirmed to be correct, while clarification is provided on the third expression involving the power set of the empty set. The fourth expression compares Cartesian products of natural and integer numbers, with a consensus that the left side contains distinct elements not found on the right. Overall, the participants engage in correcting and confirming the appropriate symbols for the given mathematical relationships.