
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
Let $U = R$, given sets $A=\{x | -2 \leq x \leq 5\}$ and $B=\{x | m+1 \leq x \leq 2m-1\}$.  
$(Ⅰ)$ When $m=4$, find $\complement _{U}(A\cup B)$;  
$(Ⅱ)$ If $B\neq \varnothing $ and $B\subseteq A$, find the range of real numbers $m$.

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