If you look in Annex B, I am allowed to use all laws from chapter 3 and below.
This is the problem itself. I did not rewrite this. If there are any missing brackets, this is how the problem was given to me. I do not know how to prove this. I can't use a truth table, I have to simplify it to an existing theorem to prove its validity.
Any help is greatly appreciated!
$\endgroup$ 21 Answer
$\begingroup$HINT
Start out observing that:
$$S \equiv [\neg (Q \land R) \land (R \rightarrow Q)] \equiv S \Leftrightarrow$$
$$S \equiv S \equiv [\neg (Q \land R) \land (R \rightarrow Q)] \Leftrightarrow$$
$$vrai \equiv [\neg (Q \land R) \land (R \rightarrow Q)] \Leftrightarrow$$
$$[\neg (Q \land R) \land (R \rightarrow Q)]$$
Now do a DeMorgan and an Implication to simplify this even further, and you're almost there!
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