Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2024/iii/paper-128/2/c/solution

Let and . Define
This is a filter: restrictions of finite pieces of remain in , and the union of two members is a common stronger condition.
To prove genericity, take a dense set . Let consist of conditions for which some satisfies
The set is dense. Indeed, given , first read its finitely many assigned even coordinates as a condition on . Choose in , and extend by setting at the remaining coordinates of . Since , the generic filter meets it. For , the corresponding is a finite subfunction of , so .
Thus meets every dense subset belonging to . Moreover, each singleton belongs to , and hence

New to topics? Read the docs here!