Natural Deduction: Negation Introduction and Negation Elimination

Program: Deductions by Wandering Mango (http://www.wanderingmango.com). Tutorial on Negation Introduction and Negation Elimination using Deductions. This tutorial is a short introduction to the negation rules in formal logic. In particular, it looks at the Fitch-style rules, as opposed to the Lemmon-style rules. It illustrates the rules by appealing to a hypothetical computer program that plays chess, but wins every game (which is contradictory, because if the program plays both sides, at least one side will not win).