How to Disprove an Existential Statement
Every argument and thus every conclusion that we may assert as TRUE needs a context ie. Proving Existential Propositions. Proving Existential Statements They are rarer but interesting. . So its enough to exhibit one concrete value. Show instead that by taking a general and showing. Which has already been discussed Similarly if we are trying to disprove an existential statement then we are actually proving a related universal statement. There are two ways to prove this. To prove x F x take an arbitrary constant a and prove F a is true. For any two real numbersaandb. Is equivalent to prove xin Dsuch that Px. We have to show that 8x 2 U. But normally a counterexample as explicit and simple as possible is the correct way to disprove a mathematical statement. To give a set of direction for finding an x that makes propositional function Qx true. X D such that propositional function Qx is true if...