Hard to get the propositional resolution

Question

I am given a premise and its resolution. But I cannot understand the steps. The premise is:

~(p|q => q|s)

and when I put that to http://intrologic.stanford.edu/applications/converter.html I get the result below:

{p,q}, {~q}, {~s}

I tried to get the same result by my hand but failed. So far I reached:

~(p | q => q | s)
(p & ~q & ~s) | (r & ~q & ~s)
(p|r) & (p|~q) & (p|~s) & ~q & ~s

But I stucked here. How can I get the final answer from here?

Answer 1

You can replace (a => b) with (~a | b):

~(p|q => q|s)

~(~(p|q) | (q|s))

(p|q) & (~(q|s))

(p|q) & (~q) & (~s)