Propositional Logic. Sentence Restrictions. Precise use of natural language is difficult . Want a notation that is suited to precision . Restrict discussion to sentences that are: declarative either true or false but not both. Such sentences are called propositions.
Which of the sentences below are propositions?
p implies q means that p causes q to be true.
If 1 1 then this class is fun.
Use a truth table to find the answer.
Thus, p q ~p ~q means
(p q) ((~p) (~q)).
If berries are ripe along the trail, hiking is safe on the trail if and only if grizzly bears have not been seen in the area.