
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
Consider the following propositions:
- Proposition ①: The negation of "If $a > b$, then $a^2 > b^2$".
- Proposition ②: The converse of "If $x + y = 0$, then $x$ and $y$ are opposites".
- Proposition ③: The contrapositive of "If $x^2 < 4$, then $-2 < x < 2$".

Among these, the true propositions are numbered __________.

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