1. Redundancy College of Alameda pmcdermott@peralta.edu Copyright © 2007 Patrick McDermott Philippe de Champaigne (1602-1647) Triple Portrait of Cardinal Richelieu (1585-1642) 1642

2. DRY Don’t Repeat Yourself Don’t Say the same Thing Twice Don’t Reiterate Don’t go over the same Ground Twice Don’t say it Again Only say it Once One time & One Time Only No Duplicate Statements

3. CW-1 Good New Lily Pat CW-2 HF-1 HF-2 HF-3 Good New Fair Johnny Mary Pat Flat 224 pagesHuck Finn1884 Mark Twain 24 pagesHick Finn1884 Sam Clemen 64 pagesCall of Wild1903 Jack London 224 pagesHuck Finn1884 Mark Twain HF-1 HF-2 HF-3 CW-1 Good New Fair Good New 88 pagesCall of Wild1907 Jack London Johnny Mary Lily Pat CW-2 224 pagesHuck Finn1884 Mark Twain 64 pagesCall of Wild1903 Jack London Database

4. Xtreme! Department –The Department of Superfluous Redundancy Department The number 7 should appear only once in the entire computer! Human languages are extremely redundant –Agree in Gender, Number & Case –Causes Numerous Grammar Errors

5. Good If computer does, OK –Don’t trust Humans (including Programmers) Replication Backup Keys Performance –Index is Always Redundant Critical or Dangerous: Triple Redundancy Belt & Braces

6. Derived Data Calculated Amount –Set Counts & Totals For Efficiency For Concept/Analysis –Don’t Forget –Reassure Users –For Data Mining “Don’t save anything you can recalculate.” —Raymond Chen, The Old New Thing

7. Unemployed In England

8. Superfluous Concept of Information Information Theory