
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given $f(x)=x^{2}-2ax+5$ ($a > 1$),  
(Ⅰ) If the domain and range of $f(x)$ are both $[1,a]$, find the value of $a$;  
(Ⅱ) If $f(x)$ is decreasing on the interval $(-\infty, 2]$, and for any $x_{1}, x_{2} \in [1,a+1]$ it always holds that $|f(x_{1})-f(x_{2})| \leq 4$, determine the range of values for $a$.

Present the answer in LaTex format: \boxed{Your answer}
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