
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
Here are several propositions:
(1) Three lines that intersect pairwise are coplanar;
(2) If one of two parallel lines is perpendicular to a certain line, then the other line is also perpendicular to this line;
(3) In space, if one side of two equal angles is parallel to each other, then the other side is also parallel to each other;
(4) There are 4 edges in a cube that are skew lines with the diagonal of a face of the cube.
Among these, the true propositions are. (Fill in the serial number only)

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