In term logic (a branch of philosophical logic), the square of opposition is a diagram representing the relations between the four basic categorical propositions. The doctrine of the square of opposition originated with Aristotle in the fourth century BC and has occurred in logic texts ever since.The proposition in Square of OppositionResultant PropositionIf 'A' is True'E' is false; 'O' is falseIf 'E' is False'I' is true; 'O' is undetermined.If 'I' is True'E' is false; 'A' is undeterminedIf 'O' is False'A' is true; 'I' is trueSo, the correct match is A-III, B ? I, C ? II, and D ? IV.Important PointsA categorical proposition is a simple proposition containing two terms, subject (S) and predicate (P), in which the predicate is either asserted or denied of the subject.Every categorical proposition can be reduced to one of four logical forms, named A, E, I, and O.The 'A' proposition, the universal affirmative usually translated as 'every S is a P'.In the proposition, the universal negative is usually 'no S is P'.The 'I' proposition, the particular affirmative usually translated as 'some S are P'.In the 'O' proposition, the particular negative is usually translated as 'some S are not P'.The propositions are placed in the four corners of a square, and the relations are represented as lines drawn between them, hence the name 'The Square of Opposition'. Therefore, the following cases can be made:If A is true, then E is false, I is true, O is false;If E is true, then A is false, I is false, O is true;If I is true, then E is false, A and O are undeterminate;If O is true, then A is false, E and I are undeterminate;If A is false, then O is true, E and I are undeterminate;If E is false, then I is true, A and O are undeterminate;If I is false, then A is false, E is true, O is true;If O is false, then A is true, E is false, and I is true.