
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 propositions, the true ones are _______  
① Two complex numbers cannot be compared in terms of size;  
② If $x, y \in \mathbb{C}$, then $x+yi=1+i$ if and only if $x=y=1$;  
③ If a real number $a$ corresponds to $ai$, then there is a one-to-one correspondence between the set of real numbers and the set of pure imaginary numbers;  
④ The complement of the set of real numbers relative to the set of complex numbers is the set of imaginary numbers.

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