"Zhiyang Xu" [email protected] wrote:

Hi, Professor:

I am doubt about that if there are two same sets like {5} and to make a union, is it ok to describe as "({5}) U ({5})".

Thank you.

The assessed lab worksheet provides instructions on how describe() should behave for each different class. It does not ask you to simplify or reformat expressions. To do so would in fact be considered wrong, as it is no longer a description of the expression, but of a different (even if equivalent) expression. There is no need to invent extra tasks for yourself that do not exist in the worksheet.

I assume it is a typo, but the example you have given is incorrect. The specification says that singletons should be formatted as "{x}" and unions as "(A U B)", so the union of a singleton 5 with a singleton 5 would be "({5} U {5})" (without the inner parentheses that you wrote).

Hope that helps.