PPT-Indirect Argument: Contradiction and Contraposition

In a direct proof you start with the hypothesis of a statement and make one deduction after another until you reach the conclusion Indirect proofs are more roundabout One kind of indirect proof . The basic idea is to assume that the statement we want to prove is false and then show that this assumption leads to nonsense We are then led to conclude that we were wrong to assume the statement was false so the statement must be true As an examp Introduction to Proofs. A . proof. is a valid argument that establishes the truth of a statement.. Previous section discussed . formal. proofs. Informal. proofs are common in math, CS, and other disciplines. Insights into literature and life. What is a contradiction?. When two things are said to coexist, but (in fact), they do not line up.. For example, when we say one thing and do another. . Examples of Contradictions. Dr. Cynthia Bailey Lee. Dr. . Shachar. Lovett. .  .                          . Peer Instruction in Discrete Mathematics by . Cynthia . Lee. is. licensed under a . Creative Commons Attribution-. August 27, 2015. Tandy Warnow. Proofs. You want to prove that some statement A is true. . You can try to prove it directly, or you can prove it indirectly… we’ll show examples of each type of proof.. Proofs that K5 and K3,3 . are not planar. Copyright © R F Barrow 2009, all rights reserved. www.waldomaths.com. K. 5. K. 3,3. The Proofs that K. 5. and K. 3,3. are not planar. Complete graph with 5 nodes. I. I. PROPOSISI. 2. Tautology and Contradiction. Definition. A tautology . is a statement . form that is always true.. A statement whose form is . a tautology is a tautological . statement. . A contradiction . Louise . Livesey. Academic Skills Adviser. This workshop . will:. Revist. what an argument is. Suggest ‘types’ of argument that an assignment can be built around. Offer strategies to apply evidence and theory into your written work. To understand one objection to indirect realism. What we’re directly aware of are our . sense data. .. . ?. Remember. If a tree falls over in a forest, and no one is there to hear it…. …does it make a noise?. Answer:. is a perpendicular bisector.. State . the assumption you would make to start an . indirect proof for the statement . . is . not a . perpendicular . bisector.. Example 1. State the Assumption for Starting an Indirect Proof. If that’s so, what is the argument here?. Every argument starts with a question.. So – what questions does this text inspire? . SOAPS is one way to start thinking about how to argue.. S = What is the subject?. Prof. Shachar Lovett. Today’s Topics:. Knights and Knaves, and Proof by Contradiction. 2. 1. Knights and Knaves. 3. Knights and Knaves. Knights and Knaves scenarios are somewhat fanciful ways of formulating logic problems. Reporting speech. . There are two ways of reporting what somebody . says:. direct speech . indirect (or reported) speech.. Direct Speech. In direct speech we use the speaker’s own words.. “In text we put speech marks around the words spoken”. Everything is an argument…. -When you hear the word “argument,” what springs to mind?. -“Argument” encompasses more than the common connotation.. -An argument can be any text—written, spoken, aural, or visual—that expresses a point of view..