TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE TRUE
FALSE FALSE TRUE

As a side note, other definitions of A Implies B (A -B) are
=OR(NOT(A1),B1)
--
HTH. :)
Dana DeLouis
Windows XP, Office 2003


"Arvi Laanemets" wrote in message
...
Hi

Into C1 enter
=OR(A1=B1,B1)
and copy down?

At least it returns wanted result for your example data. To get a true
answer, you have to ask better. This particular formula is an answer to a
task:
"Find the formula, which returns TRUE, whenever both entries in column A
and
B are same (TRUE OR FALSE), or when the entry in column B is TRUE". As you
easily can see, a task set properly often contains an answer.

Arvi Laanemets


"mikebispham"
wrote in message
...

Hi Arvi

The result I'm looking for (in the first instance) is the truth-table
for what is known in philosophy as the 'material condition':

TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE TRUE
FALSE FALSE TRUE

The third column (C) results from the combination of the first two, and
is ideally where the formula should reside. Its symbolised (in
philosophy) by A(arrow) B

Your "=OR(B11=C11,B11=A11)" works when the first column is B, the A
left blank and the results and formular in D

Your formular "=IF(OR(B11=C11,B11=D11),TRUE,FALSE)" works if D is left
blank and the formular placed in E... (or elsewhere)

I can't make the other two produce the right result. I'd prefer a
tidier solution where the formular residing in C tests A and B.

_______

The bi-conditional, written A(arrow pointing both ways)B produces the
following truth-table:

TRUE TRUE TRUE
TRUE FALSE FALSE
FALSE TRUE FALSE
FALSE FALSE TRUE

It means 'if and only if' (sometimes written iff). As you can see it
just wants to know if both A and B are the same.

I do hope that helps, and I'm sorry I don't know the lingo. As I say
I'm a philosophy student, and I'm using the terms I've been taught for
purposes of 'logical thinking'. We're supposed to apply these tests to
the components or arguments written in english, in order to discover if
they are 'sound' and 'valid'.

Again, thanks so very much for your help this far!

Mike


--
mikebispham
------------------------------------------------------------------------
mikebispham's Profile:
http://www.excelforum.com/member.php...o&userid=31180
View this thread:
http://www.excelforum.com/showthread...hreadid=508424