Me and David C. Ullrich

On this forum I have argued the question, "Two coins were flipped and
at least one is a head. What are the chances that there are two heads?"

Many mathematicians get it confused with "The probability for two
heads, given at least one head?"

I say that "given at least one head", and told, "at least one head"
mean two different things.

Dr. Ullrich has stated in this forum, that the two mean the same thing.
If for no other reason than that he said so. Also because everyone
assumes them to be the same. (everyone does not, I don't)

I had occasion to visit Oklahoma State University. I found Dr. Ullrich
in the Student Center. He said I was not welcome there. He refused to
discuss the question with me there, as he has refused to discuss it
here.

The probability for two tails, given at least one tail is one third.
That is defined mathematically and is not arguable.

What it means to say, "at least one is a tail" is defined in the world
domain and means what it says. As the math domain is a subset of the
world domain, it is not possible to re-define, inside the math domain,
what "at least one is" means in the outside world.

An example:

Suppose that a computer program randomizes the coins, or dice, or puppy
dogs. Then shows us to colors. Suppose that we see a red and an orange.

We can make the statement"there are two colors and at least one is red"
or we can make the statement "there are two colors and at least one is
orange." The red statement tells nothing of orange, and the orange
statement tells nothing of red.

The statements "at least one is red" and "at least one is orange"
demonstrate what it means to say "at least one is".

Now make the statement, "There are two colors, given at least one red."
Does that mean the same thing as "There are two coins, given at least
one head"? If it does, then the probability for two reds is 1/3. To
mean the same thing as "given at least one", the 'red' statement must
convey some knowledge of 'orange' and the 'orange' statement must
convey some knowledge of 'red'.

Dr. Ullrich seems to be somewhat of a fakir. He plays a lot of
bachgammon.
He argues a lot in this forum.
He does not seem to publish.
He draws a paycheck at OSU, I guess, wonder if he has tenure?

When you accept that "given at least one" and told, "at least one" are
different; then it's easy to get from:

P(hh|at least one h) = 1/3 to
P(hh|told "at least one h) = 1/2.

Eldon Moritz
elmoritz@xxxxxxxxx

.

Relevant Pages

  • Re: Me and David C. Ullrich
    ... What are the chances that there are two heads?" ... > Dr. Ullrich has stated in this forum, that the two mean the same thing. ... > Suppose that a computer program randomizes the coins, or dice, or puppy ... then the probability for two reds is 1/3. ...
    (sci.math)
  • Re: Me and David C. Ullrich
    ... > Eldon, the timing is implied by what you wrote: ... > "On this forum I have argued the question, ... > least one of the coins is a head. ...
    (sci.math)
  • Re: Me and David C. Ullrich
    ... the timing is implied by what you wrote: ... "On this forum I have argued the question, ... least one of the coins is a head. ...
    (sci.math)
  • Re: Me and David C. Ullrich
    ... >>On this forum I have argued the question, "Two coins were flipped and ... >>at least one is a head. ... and the natural interpretation is that this condition ...
    (sci.math)
  • Re: Me and David C. Ullrich
    ... >On this forum I have argued the question, "Two coins were flipped and ... >at least one is a head. ... What are the chances that there are two heads?" ...
    (sci.math)