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Unformatted text preview: Lecture 4: Truth functions, evaluating compound statements 1. Functions, arithmetic functions, and truth functions 2. Definitions of truth functions 3. Evaluating compound expressions 4. Categorizing statements Functions A function is something that takes inputs and produces outputs. You can think of them as a sort of abstract machine  like a bread machine that will produce as ‘output’ bread, if it is given as ‘input’ flour, yeast, sugar, etc. Arithmetic Functions Familiar examples of functions are the arithmetic functions addition, subtraction, multiplication and division Addition takes 2 numbers as input, and produces 1 number as output If you input 4 and 3, it outputs 7 Addition takes 2 numbers as input, and produces 1 number as output If you input 4 and 3, it outputs 7 A function can be defined in terms of its entire inputoutput structure x y x+y 1 1 2 1 2 3 2 1 3 2 2 4 A function can be defined in terms of its entire inputoutput structure x y x+y 1 1 2 1 2 3 2 1 3 2 2 4 x y x 㱸 y 1 1 2 1 2 3 2 1 3 2 2 4 Addition ‘+’ Rickification ‘ 㱸 ’ x y x+y 1 1 2 1 2 3 2 1 3 2 2 4 Addition ‘+’ x y x x y 1 1 1 1 2 2 2 1 2 2 2 4 Multiplication ‘x’ x y xy 1 1 1 21 2 1 1 2 2 Subtraction ‘’ x y x ÷ y 1 1 1 1 2 .5 2 1 2 2 2 1 Division ‘+’ Truth Functions Truth functions are functions that take truth values as inputs, and produce truth values as outputs....
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This note was uploaded on 09/07/2011 for the course PHIL 10 taught by Professor Churchland during the Spring '08 term at UCSD.
 Spring '08
 churchland

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