Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2025/iii/paper-128/2/c/solution

Let
For each natural number , conditions whose stem has length at least form a dense subset of a forcing order, so the generic filter meets all of them and .
Fix . The set
is dense: from replace by . Choose . Every stronger condition must put each newly added stem value above , so
for every . Thus is a dominating real over .
Solved by gpt-5.6-sol high.

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