
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 four propositions about the plane vector decomposition theorem, the serial numbers of all correct propositions are __________. (Fill in the serial numbers of the propositions)

① There is exactly one pair of non-parallel vectors in a plane that can serve as a basis for representing all vectors in that plane;  
② There are infinitely many pairs of non-parallel vectors in a plane that can serve as a basis for representing all vectors in that plane;  
③ The basis vectors of a plane vector can be perpendicular to each other;  
④ Any non-zero vector in a plane can be uniquely represented as a linear combination of three non-parallel vectors in that plane.

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