\[ \text { Let } \begin{aligned} U & =\{1,2,3, \cdots\} \\ A & =\{1,2,3, \cdots, 26\} \end{aligned} \] VHL Central I Voc... Use the roster method to write the set $A^{\prime}$. \[ A^{\prime}= \] (Use a comma to separate answers as needed. Use ascending order.)

Step 1 ：Let \( U = \{1,2,3, \cdots\} \) and \( A = \{1,2,3, \cdots, 26\} \).

Step 2 ：Use the roster method to write the set \( A^\prime \).

Step 3 ：Without a clear definition of the universal set \( U \), we cannot determine the exact elements of \( A^\prime \).

Step 4 ：If we assume that \( U \) contains all natural numbers, then \( A^\prime \) would contain all natural numbers greater than 26. But this is just an assumption.

Step 5 ：\( \boxed{\text{Therefore, the final answer is undefined.}} \)