
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
Among the following functions, the one that is monotonically decreasing in the interval $(0,1)$ is ______. (Fill in the serial number)

① $f(x)=\sin x$；

② $f(x)=x+ \dfrac{1}{x}$；

③ $f(x)=\log_{\frac{1}{2}}(x+3)$；

④ $f(x)=|x+1|$．

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