 Constructive mathematicians not working in ML typically reject the full axiom of choice but embrace the axiom of countable choice, in which the domain of choice is \(\bN\), and dependent choice. But some prefer to work without even countable choice, on the grounds that to speak of an infinity of choices without giving a rule presents a difficulty that is just as great whether or not the infinity is denumerable. Interestingly, Lebesgue made precisely this point in a letter to Borel (see Moore [2013], page 316): 