
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 that the function $f(x)$ is an even function defined on $\mathbb{R}$, and when $x \geqslant 0$, $f(x)=( \frac {1}{2})^{x}$.
(I) Find the value of $f(-1)$;
(II) Find the range of the function $f(x)$, denoted as $A$;
(III) Let the function $g(x)= \sqrt {-x^{2}+(a-1)x+a}$ have a domain of set $B$. If $A \subseteq B$, find the range of values for the real number $a$.

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