A mathematics-based, crossword puzzle SYSTEM. Volume 1 of 3. A complete explanation of and solution to an Abstract Crossword puzzle. Plus all of the four-letter words and the six-letter words in play enumerated every which way with statistics. Introduces the novelty of 2D Regular Expressions Across and down, simultaneously. Seniors, when you sign up for Medicare coverage of your physical health, at the same time purchase this series of mental exercises to sharpen and re-sharpen your brain on a regular basis.