Written on July 4, 2002 (2 WE).

There has always been a great interest in ** combination**. There is a branch of mathematics named

Two major difficulties in combinatorics are related to two factors:

1) Determining theoretically the rank (or lexicographical order, or index) of a given combination;

2) Constructing theoretically the combination of a given rank (index).

The first attempt to address the major issues came in 1974. B.P. Buckles and M. Lybanon created a computer program to construct a combination when the rank is known (algorithm *ACM #515*). It is a great achievement. The authors of that algorithm, however, were unable to reverse the procedure and determine the rank for a given combination.

I was the first to solve the problem. I did it in 2001. I wrote the computer program SEQUENCE.EXE. I presented the core of my algorithm in the message:

My algorithm did not cover an important combinatorics field: Powerball/Mega Millions. It is a different and difficult lotto game. It draws 5 or 6 numbers like in any regular lotto game. Then it draws separately a so-called *power ball* or *mega ball* that can be equal to or less than any regular number previously drawn.

The two major issues were so difficult that nobody came even close to solving them. I took a superficial look at the issues. I thought I would be able to solve the puzzle quite easily. I moved the task to the back burner because I've always had projects I consider more important than others. Then I forgot about it

The Powerball lexicographic algorithm didn't work out the first day. If I can't come out with a solution the first day, chances are there is no solution. Almighty Number grants us one unit of Light and one unit of Darkness to carry out important tasks.

COLORDER.EXE

with the description:

I verified the combinatorial algorithm with many cases. I believe the procedure is 100% accurate. But, if you think you discovered a miscalculation, please let me know. Please document the error(s) as detailed and as clearly as possible. I believe I can fix the errors if any. Also importantly, I always express my gratitude to people who discover genuine errors in my software, systems, strategies, theories; e.g. I offer freebies not available to every visitor to my Web site.

My lexicographic software is now at its peak of comprehensiveness and accuracy: LexicographicSets.exe.

This is a comprehensive list of my writings on the topic of lexicographical order or indexing, including algorithms and software.

This is the most intuitive, if not the best, introduction to the apparently difficult concept of lexicographic ordering (or indexing).

This is the most comprehensive and intuitive presentation of the concept of lexicographic ordering (or indexing), including the superior software to tackle the task.

This is how it all started. I responded to challenges in various newsgroups. I came up with the complementary algorithm to the original algorithm by B.P. Buckles and M. Lybanon" (algorithm "ACM #515"). I offered my lexicographic algorithm bona fide to ACM. A bunch of suckers there tried to make my algorithm look like their creation, not mine!

The introduction of DrawIndex.EXE, the software that calculates the lexicographic indexes for every combination (draw) in a lotto results file.

The following are older and somehow outdated materials I wrote on lexicographical order subjects. Most of the older software is outdated. Nothing (in the whole world) can beat LexicographicSets.EXE or DrawIndex.EXE. Sentimentalism is good only to a close extent.

Of course, everybody loves to feast on great software, especially when it is free! My combinatorics software (and other categories) is absolutely free to run, for an unlimited period of time. However, only the registered members have a right to download the software. Membership requires a nominal fee the most reasonable there is to connect to the greatest and most useful software ever created. No kidding! Read the conditions to becoming a registered member: Download Great Free Software: Paid Membership Required.

**Download Lexicographical Software, plus much more:**

LexicographicSets.EXE, the universal permutations, arrangements and combinations lexicographic indexing (ranking);

DrawIndex.EXE - highly automated lexicographical indexing for lotto draw files.

NthIndex.EXE ~ lexicographic indexing superseded by LexicographicSets.EXE;

SEQUENCE.EXE ~ lexicographic indexing superseded by LexicographicSets.EXE;

COLORDER.EXE - lexicographical indexing for lotto and Powerball only;

PermuteCombine.exe, the universal permutations, arrangements and combinations generator for any numbers and words;

Combinations.exe, the universal combinations generator for any lotto, Keno, Powerball game: N numbers taken M at a time, in K steps;

WRITER.EXE, random generator of letters to words, passwords, sentences;