
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 statement "Lines a and b are skew lines" means: ①$a \cap b = \emptyset$, and $a$ is not parallel to $b$; ②$a \subset$ plane $\alpha$, $b \subset$ plane $\beta$, and $a \cap b = \emptyset$; ③$a \subset$ plane $\alpha$, $b \subset$ plane $\beta$, and $a \cap \beta = \emptyset$; ④$a \subset$ plane $\alpha$, $b \nsubseteq$ plane $\alpha$; ⑤There does not exist a plane $\alpha$ such that $a \subset \alpha$ and $b \subset \alpha$. The correct sequence numbers are.

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