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Discrete Mathematics University of Kentucky CS 275 Spring ... - MGNet

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Notation: Timing, as a function <strong>of</strong> the number <strong>of</strong> elements falls into the field <strong>of</strong><br />

Complexity.<br />

Complexity Terminology<br />

>(1) Constant<br />

>(log(n)) Logarithmic<br />

>(n)<br />

Linear<br />

>(nlog(n)) nlog(n)<br />

>(n k )<br />

Polynomial<br />

>(n k log(n)) Polylog<br />

>(k n ), where k>1 Exponential<br />

>(n!)<br />

Factorial<br />

Notation: Problems are tractable if they can be solved in polynomial time and<br />

are intractable otherwise.<br />

41<br />

Algorithms, Integers, and Matrices<br />

Definition: An algorithm is a finite set <strong>of</strong> precise instructions for solving a<br />

problem.<br />

Computational algorithms should have these properties:<br />

• Input: Values from a specified set.<br />

• Output: Results using the input from a specified set.<br />

• Definiteness: The steps in the algorithm are precise.<br />

• Correctness: The output produced from the input is the right solution.<br />

• Finiteness: The results are produced using a finite number <strong>of</strong> steps.<br />

• Effectiveness: Each step must be performable and in a finite amount <strong>of</strong><br />

time.<br />

• Generality: The procedure should accept all input from the input set, not<br />

just special cases.<br />

42

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