
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 the function $f(x)=|x-2|+|x-a^{2}|$.  
$(1)$ If the inequality $f(x)\leqslant a$ has solutions for $x$, find the range of the real number $a$;  
$(2)$ If the positive real numbers $m$, $n$ satisfy $m+2n=a$, when $a$ takes the maximum value from $(1)$, find the minimum value of $\left( \dfrac {1}{m}+ \dfrac {1}{n}\right)$.

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