
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 $A=\{1, 2, 3, 4\}$, $f(x)=\log_{2}x$, $x \in A$  
(1) Let set $B=\{y|y=f(x)\}$, please represent set $B$ using the enumeration method;  
(2) Find $A \cap B$ and $A \cup B$.

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