
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
For the curve $x^4 + y^2 = 1$, consider the following four statements:  
① It is symmetric about the x-axis and y-axis;  
② It has exactly one center of symmetry;  
③ It is closed and its area is greater than $\pi$;  
④ It is closed and its area is less than $\pi$. Among these, the correct statements are.

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