Im confused by coursework 6, question 2. What is it asking for?
Let’s start with some set theory. • N is a set of symbols (the nonterminals). • T is a set of symbols (the terminals). • (N ∪ T) is the set of nonterminals unioned with the set of terminals, so the set of all terminal and nonterminal symbols. • The star means zero or more elements of the set concatenated together, so (N ∪ T)* is the set of all possible strings made up of any number of terminal and nonterminal symbols (an infinite set). • × is the cartesian product of two sets. So in the case of this question, both of those sets are the same infinite set of strings (N ∪ T)*. The cartesian product is the set of all pairs such that the first element is drawn from the first set, and the second element is drawn from the second set. Formally, (N ∪ T)* × (N ∪ T)* = { (α,β) | α ∈ (N ∪ T)* ∧ β ∈ (N ∪ T)* } So this is another infinite set, made up of all possible pairings. • In set theory, sets of pairs are used to denote relations. Each pair relates the left element to the right element. So thi
