Morgan Worthy (http://mworthy.home.mindspring.com/) originated the puzzle form now called "linguistic equations" or "DITLOIDS" (see entry for 1, below). The first ones were published in his 1975 book, "AHA! A Puzzle Approach to Creative Thinking" (Chicago: Nelson Hall) - now out of print.

Here are his comments on how he thought of the idea in the first place,

and why they have become such perennial favorites

I got the idea for linguistic equations from graffiti someone had written in the form of an obscene formula on a restroom wall at the University of Florida. When the answer suddenly came to me, I realized the format was a good one for eliciting the "aha effect". After that I used such items as exercise material when teaching workshops on creative thinking.

My guess is that one reason a person enjoys linguistic equations is that the answer hits him or her all at once rather than being solved in an incremental fashion. It is similar to what happens when we suddenly see an embedded figure pop into focus; the satisfaction is visceral rather than just intellectual. My experience was that people often had the answer to an item come to them when they were not consciously thinking about the puzzles, but relaxed, such as in the shower or about to fall asleep.

Another factor is that with well-written items, success does not hinge on obscure information. Ideally, a person should never have to feel, "I could never have gotten that one no matter how long I worked on it." There is something ego enhancing about knowing you have the answer inside and just need to find it.

Morgan Worthy

From his book, here is the original "Formula Analysis Test - Revised Form,"

1. M.+M.+N.H.+V.+C.+R.I = N.E.

Maine + Massachusetts + New Hampshire + Vermont + Connecticut + Rhode Island = New England

2. "1B. in the H. = 2 in the B."

"One Bird in the Hand Equals Two in the Bush."

3. 8D. - 24H. = 1W.

8 Days - 24 Hours = 1 Week

4. H.H.& M.H. at 12 = N. OR M.

Hours Hand & Minute Hand at 12 = Noon or Midnight

5. 3P. = 6

3 Pair = 6

6. 4J. + 4Q. + 4K. = all the F.C.

4 Jacks + 4 Queens + 4 Kings = all the Face Cards

7. S. & M. & T. & W. & T. & F. & S. are D. of W.

Sunday & Monday & Tuesday & Wednesday & Thursday & Friday are Days of Week

8. A. + N. + A.F. + M.C. + C.G. = A.F.

Army + Navy + Air Force + Marine Corps + Coast Guard = Armed Forces

9. T. = L.S. State

Texas = Lone Star State

10. 23Y. 3Y. = 2D.

23 Years - 3 Years = 2 Decades

11. E. 8 = Z.

Eight - 8 = Zero

12. 8P. = 1G.

8 Pints = 1 Gallon

13. C. + 6D. = N.Y.E.

Christmas + 6 Days = New Year's Eve

14. S.R. of N. = 3

Square Root of Nine = 3

15. A. & E. were in the G. of E.

Adam and Eve were in the Garden of Eden.

16. My F.L. & South P. are both M.C.

"My Fair Lady" and "South Pacific" are both Musical Comedies

17. "N.N. = G.N."

"No News is Good News."

18. N. + P. + S.M. = S. of C

Nina + Pinta + Santa Maria = Ships of Columbus

19. 1 + 6Z. = 1M.

One + 6 Zeros = 1 Million

20. B. or G. F. M. = O.

Boy or Girl - Father - Mother = Orphan

21. "R. = R. = R."

"A Rose is a Rose is a Rose."

22. A.L. & J.G. & W.M. & J.K. were all A.

Abe Lincoln & James Garfield & William Mc-Kinley & John Kennedy were all Assassinated

23. N. + V. +P. + A. + A. + C. + P. + I. = P. of S.

Noun + Verb + Pronoun + Adjective + Adverb + Conjunction + Preposition + Interjection = Parts of Speech

24. S. + H. of R. = U.S.C.

Senate + House of Representatives = United States Congress

25. P. & N. & D. & Q. & H.D. are all C.

Penny & Nickel & Dime & Quarter & Half Dollar are all Coins

26. Y. S. S. A. = W.

Year Summer Spring Autumn = Winter

27. Y. + 2D. = T.

Yesterday + 2 Days = Tomorrow

This puzzle form reappeared as 24 "equations" by Will Shortz, printed in the May-June 1981 issue of Games magazine, with an acknowledgement to Morgan Worthy. Games ran several followups in subsequent issues, and reported that people kept resubmitting the puzzle to them, sometimes as original work! Many people have now added to the list of equations. The 24 original ones are starred (*) below.

A few more comments are needed about the esthetics of this type of puzzle in addition to those of Morgan Worthy above. A good letter equation emphasizes the uniqueness of the number on the left-hand side of the equation, and is not merely one in a long series of equations. For example, the equation 79 = AN of G = Atomic Number of Gold is excluded from the following collection, along with equations involving atomic weights, levels on some scale, years in which well-known events occurred, powers of integers, etc. The left-hand side must be an exact integer, thus 18.5 = ME from the WT = Minutes Erased from the Watergate Tapes is excluded, along with fundamental constants, non-integral conversion factors between units of measure, well-known dimensions, etc. Also, the left hand side cannot be a concatenation of digits, such as 12 = BMS = Buckle My Shoe.

There are a couple of conventions that we recommend but that are not universally observed. If a number occurs on the right-hand side of the equation, it is spelled out (as in 1 = B in the HWT in the B = Bird in the Hand Worth Two in the Bush). Finally, unlike Worthy, we do not put periods after the initial letters and we do concetenate consecutive ones ("BLSB" not "B L S B").

79 is the first number for which there is no entry.