
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
Given the following propositions:
① There is exactly one line through a point outside a plane that is perpendicular to the plane;
② There is exactly one line through a point outside a plane that is parallel to the plane;
③ If two parallel planes intersect a third plane, then the two lines of intersection are parallel;
④ If two planes are perpendicular to each other, then a line passing through a point in the first plane and perpendicular to the second plane must lie within the first plane.
The sequence numbers of all true propositions are.

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