Re: Truth Tables Help

From: One Weird Dude (im2_weird_at_yahoo.com)
Date: 10/15/04 

Date: 14 Oct 2004 18:04:45 -0700

"BIGEYE" <email@ddres.is.invalid> wrote in message news:<416ec61b$0$44840$ed2619ec@ptn-nntp-reader02.plus.net>...
> My earlier post should read:
> I have a four part question in a tutorial, parts 1 & 2 I don't have any
> problem with. Parts 3 & 4 I have no idea what they mean. Can someone explain
> to me what parts 3 & 4 mean and how can I answer the questions.
> Alternatively if you can point me to a website that might be of some help.
> The question:
> Draw the truth tables for each of the following expressions:
> 1. AB'CD' + ABC'D' + A'BC'D + A'B'CD
> 2. (A + B' + C' + D)(A' + B + C + D')
> 3. Sigma m(2.5.6.9)
> 4. Pi M(0,7,10,11)
>
> 3 & 4 should read:
> _
> \
> /_ m (2.5.6.9)
>
> __
> I I M (0,7,10,11)
> Appreciate any help.
> TIA

I worked out 1 and 2 and found a shortcut I should have used once I
was halfway done. Oh well.

Capital Sigma means sum. Example: [Cap. Sigma x] means, in Stats, the
sum of all x values. [Cap. Sigma x^2] is the sum of the squares of
all x values. You knew that, I imagine.

Outside of Stats, Cap. Sigma is an iterated sum. Example: Draw a
Capital Simga on the chalkboard. Below it, write "n = 1". Above the
Sigma, write 12. To the right of the Sigma, write "(2n-1)". The
resulting expression (which I wish I could write instead of describe)
is the sum of the odd numbers 1, 3, 5, ... 23, which adds up to 144,
which is 12 squared. (Partly because 12 is on top.) Again, you
probably already knew this.

My guess for number 3 is based on the second one. Represent each
number in that list (i.e. 2, 5, 6 & 9) in binary, and "add" the
corresponding digits; that is, use the last digit as values of D, as
it were, the third digit for C, and so on. Ex. 0101 + 1100 = 1101.
This is just my guess. Sorry I can't be more helpful.

For number 4, Capital Pi is the same thing, except it's iterated
multiplication. Problem is, now I can't come up with _any_ sensible
explanation. Sorry. 

--
Dude.  One weird.

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