Editing De Morgan's laws (section)

===Negation of a disjunction===
In the case of its application to a disjunction, consider the following claim: "it is false that either of A or B is true", which is written as:
:<math>\neg(A\lor B).</math>
In that it has been established that ''neither'' A nor B is true, then it must follow that both A is not true [[logical AND|and]] B is not true, which may be written directly as:
:<math>(\neg A)\wedge(\neg B).</math>
If either A or B ''were'' true, then the disjunction of A and B would be true, making its negation false. Presented in English, this follows the logic that "since two things are both false, it is also false that either of them is true".

Working in the opposite direction, the second expression asserts that A is false and B is false (or equivalently that "not A" and "not B" are true). Knowing this, a disjunction of A and B must be false also. The negation of said disjunction must thus be true, and the result is identical to the first claim.