Propositional Logic


Subjects to be Learned


Sentences considered in propositional logic are not arbitrary sentences but are the ones that are either true or false, but not both. This kind of sentences are called propositions.

If a proposition is true, then we say it has a truth value of "true"; if a proposition is false, its truth value is "false".

For example, "Grass is green", and "2 + 5 = 5" are propositions.
The first proposition has the truth value of "true" and the second "false".

But "Close the door", and "Is it hot outside ?"are not propositions.

Also "x is greater than 2", where x is a variable representing a number, is not a proposition,
because unless a specific value is given to x we can not say whether it is true or false.

Test Your Understanding of Proposition

Which of the following sentences are a proposition ?

Click Yes or No , then Submit. There are two sets of questions.

Next -- Elements of Propositional Logic

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