
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 four statements  
① The solution set of the inequality $\sqrt {x+1}(2x-1) \geq 0$ is $\{x|x \geq \frac {1}{2}\}$;  
② "x > 1 and y > 2" is a sufficient but not necessary condition for "x + y > 3";  
③ The function $y= \sqrt {x^{2}+2}+ \frac {1}{ \sqrt {x^{2}+2}}$ has a minimum value of 2;  
④ The negation of the proposition "∃x ∈ \mathbb{R}, such that $x^2 + x + 1 < 0$" is "∀x ∈ \mathbb{R}, $x^2 + x + 1 < 0$".  
The true statement(s) is/are __________ (fill in the correct proposition number(s)).

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