
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
Let the function $f(x)$ ($x \in \mathbb{R}$) have a period of $3$. When $x \in [-2,1)$, $f(x)$ is defined as follows:
\[f(x)= \begin{cases} x+a, & -2\leqslant x < 0 \\ ( \dfrac {1}{2})^{x}, & 0\leqslant x < 1\end{cases}\]  
1. Find $f( \dfrac {13}{2})=$ \_\_\_\_\_\_ ;  
2. If $f(x)$ has a minimum value but no maximum value, then the range of the real number $a$ is \_\_\_\_\_\_ .

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