
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
Factorize:  
(1) $x^4-y^4$  
(2) $x^3y-2x^2y^2+xy^3$  
(3) $4x^2-4x+1$  
(4) $4(a-b)^2+1+4(a-b)$

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