
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 following four propositions:<br/>①Vertical angles are equal;<br/>②Complementary angles of equal angles are equal;<br/>③If $b$ is parallel to $a$ and $c$ is parallel to $a$, then $b$ is parallel to $c$;<br/>④Corresponding angles are equal.<br/>Among them, the correct statements are ______.

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