
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
Among the following four propositions:
① If four points in space are coplanar, then there must be three points that are collinear;
② If among four points in space, three points are collinear, then these four points must be coplanar;
③ If among four points in space, any three points are not collinear, then these four points are not coplanar;
④ If four points in space are not coplanar, then any three points are not collinear.
The correct proposition numbers are $\boxed{\text{②④}}$.

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