
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 In space, there are countless points whose distances to the sides of a triangle are equal;
② In space, there are countless points whose distances to the sides of a rectangle are equal;
③ In space, there are points that are equidistant from all vertices of a rectangular solid, and there are points that are equidistant from all its faces;
④ In space, there are points that are equidistant from all vertices of a tetrahedron, and there are points that are equidistant from all its faces.
The serial numbers of the true propositions are. (Write down the serial numbers of all true propositions)

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