
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 that $F$ is the focus of the parabola $E$: $x^{2}=2py (p > 0)$, and the line $l$: $y=kx+ \frac{p}{2}$ intersects the parabola $E$ at points $A$ and $B$.
(I) When $k=1$, and $|AB|=8$, find the equation of the parabola $E$.
(II) Draw tangents $l_{1}$ and $l_{2}$ to the parabola $E$ passing through points $A$ and $B$, intersecting at point $P$. If the sum of the slopes of line $PF$ and line $l$ is $-\frac{3}{2}$, find the slope of line $l$.

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