
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
Given the sets $A=\{2,5,a+1\}$ and $B=\{1,3,a\}$, and $A\cap B=\{2,3\}$  
(Ⅰ) Find the value of the real number $a$ and $A\cup B$;  
(Ⅱ) Let the universal set $U=\{x\in\mathbb{N}|x\leqslant 6\}$, find $(\complement_{U}A)\cap(\complement_{U}B)$.

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