
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
Given the universal set $U=\mathbb{R}$, let set $A=\{x|x^2-2x-3>0\}$, and $B=\{x|4-x^2\leq0\}$. Find:  
(1) $A\cap B$;  
(2) $(\complement_U A) \cup (\complement_U B)$.

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