April 30, 2002: I mailed DFF Newsletter
#26 yesterday with graphics missing -actually embedded as
links to their Internet home. Here's my defense: I
switched to MS Outlook mail program this month and misinterpreted
one of the options. "Send pictures from Internet"
option means "Include the pictures with email" , not
"Leave pictures on the Internet" as I
assumed. Also we have DSL broadband service up on our mountain
now (!), so the fact that it was downloading the pictures during my
test wasn't obvious. I apologize if your mail
reader tries to access the Internet to get those
graphics. It's corrected for next time and
probably not worth resending the current issue since graphics all appear
below anyway.
April
29, 2002: Here's Nim 2, the
multi--pile version of that take away game. This was
originally intended to be an more challenging implementation of the
Minimax search technique described last week. But it turns out that there
is an even cooler algorithm based on the binary representations of the
number of sticks in each pile. It's good enough to let the computer
defeat mere mortals most of the time.
April 26, 2002: I've been doing some
housekeeping - among other things the indices in the Programs
section of the site are now in alphabetical order. I also
updated Permutes 1, a program
introducing permutations, the ways that a set of objects or numbers can be
arranged. And the new entry is Permutes
2 which adds the ability to permute subsets of a set of
numbers, and combinations, the ways to select subsets if order
doesn't matter. Permutes 2 also includes and tests the
Combo unit, a unit providing a convenient interface for permutation
and combination generation.
April 24, 2002: Jerry Pournelle of Byte
magazine fame, features a Book of the Month in each
column; maybe I'll start doing the same. This
month it would definitely be Martin Gardner's The Colossal Book of
Mathematics, W.W.Norton, & Co., 2001. It's a
collection selected by Gardner of the his 50 best "Mathematical
Recreations" columns originally printed in Scientific American
magazine. This is the 17th published anthology of those
columns, but if you are going to own only one, this is probably
it.
Chapter
3, "Palindromes: Words and Numbers" led directly to today's
program, the third in the T-Shirt series, T-Shirts
#3, Back of the shirt reads: "The only known
non-palindromic integer whose cube is a palindrome"
The number on the front is ???. Palindromes, by the
way, are numbers (or words or sentences) that read the same
from either end.
April 21, 2002: This week we're
beginning the investigation of a fairly major topic in the world
of Computational Game Theory: minimax search
of game trees. Minimax is a technique for finding good moves for
a large class of two player games. Today's implementation is
NIM, a simple game that meets the minimax
criteria.
Players alternate removing 1, 2, or 3 sticks from a pile; the
player taking the last one loses. Two hundred or so lines of
code are enough to get the Delphi programmer started.
Non-programmers are welcome to download and play the executable version,
but more interesting games of this type will
follow.
April 14, 2002: Here's the link to the interesting online article,
"Learn
to Program in 10 Years", that I mentioned a few
weeks ago. Just ran across the reference so thought
I had better post it before it disappeared again.
I posted a demo today over in Delphi Techniques
showing how to include Animated
Cursors in Program Resource files. I
haven't figured out how to use animated cursors on Web pages yet though
- probably a blessing in disguise.
April
8, 2002: Here's the last version of Hangman: Hangman
2 - The Tricky Hangman. It adds a dictionary and computer play to
the earlier version. The program plays the role of Convict about the
same way as humans - it just does it better. As Hangman, the
program selects a random word from the dictionary and scores Convict
responses. The "Tricky" Hangman may bend the rules
just a little (but only to ensure that justice is
served).
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