
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
The ellipse $$\frac {x^{2}}{4}+y^{2}=1$$ has two foci, denoted as $F_1$ and $F_2$. If point $P$ is any point on the ellipse, then the range of values for $$\overrightarrow {PF_{1}}\cdot \overrightarrow {PF_{2}}$$ is \_\_\_\_\_\_ .

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