
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
In the functions $f(x)=2^{x}$, $f(x)=(\frac{1}{2})^x$, $f(x)=\ln x$, $f(x)=\frac{1}{x}$, $f(x)=-\sqrt{x}$, which of the functions satisfy the condition that for any $x_{1}$ and $x_{2}$ in the domain with $x_{1} \gt x_{2}$, $\frac{f(x_1)-f(x_2)}{x_1-x_2}＜2$? (Please fill in the blank with the numbers of the functions that meet the condition.)

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