
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
(1) Given that line $l_1: 2x + (m+1)y + 4 = 0$ is parallel to line $l_2: mx + 3y - 2 = 0$, find the value of $m$;  
(2) Given that line $l_1: (a+2)x + (1-a)y - 1 = 0$ is perpendicular to line $l_2: (a-1)x + (2a+3)y + 2 = 0$, find the value of $a$.

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