
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
This year, our school honored 19 outstanding youths on Youth Day. Among them, students A, B, C, and D are to be arranged in a row in any order for a photo. Calculate the probability of the following events:
(1) Student A is at one end.
(2) Both A and B are at the ends.
(3) Either A or B is at one end.
(4) Neither A nor B is at one end.

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