# Reversability of the 40 Principles of Problem Solving

Todd Williams
3M Corporation, St. Paul, MN
trwilliams@mmm.com

Ellen Domb
The TRIZ Institute, 190 N. Mountain Ave., Upland, CA 91786 USA
+1(909)949-0857 FAX +1(909)949-2968 ellendomb@compuserve.com

The 40 Principles of problem solving are among the oldest tools of TRIZ, and are used by most students of TRIZ when they first learn the basic TRIZ problem solving methods. (For a downloadable list of the 40 principles, with examples, see the article "Contradictions" in the July, 1997 issue of The TRIZ Journal.) They are included in all the commercial TRIZ-related software, and in the popular books available in English. (References 1,2,3,4,5,6)

The principles were developed during the initial patent research by H. Altshuller and his research colleagues, and provide methods, with examples, for solving large classes of inventive problems. The 40 principles themselves display both symmetry and asymmetry; that is, some of them are reversible (Principle 1, segmentation, and Principle 5, merging) and some are not (Principle 40, Use composite materials.)

The table below is a listing of the 40 principles, the opposite to each principle if one is obvious, and some examples of the opposite. We invite readers of this journal to contribute their own suggestions for completing the table. We have found that this is a useful exercise for classes in which people are learning the 40 principles for the first time.

We have speculated that the asymmetry of the 40 principles arose because these are principles for solving INVENTIVE problems, and the opposites may be the solutions for ordinary problems. (For example, use homogeneous materials is the opposite of use composite materials, but is not an inventive solution. Substitute fields for mechanical means is inventive, use mechanical means only is not, etc. ) We invite readers who participated in the research to write and let us know the history of the asymmetry of the 40 Principles. Please send you comments to editor@triz-journal.com