On Dec 28, 2011, at 3:15 AM, peter dalgaard wrote:
On Dec 28, 2011, at 05:11 , Matilda E. Gogos wrote:
Hello,
This is a question from a class I'm not in (it's also winter
break). But,
all the same, I don't know where to start in R with this. It's
supposed to
be done in R. So, can anyone direct me with a helpful hint or 2,
on how to
get started with the question listed below, or tell me how I can re-
post
this to Usenet groups sci.stat.consult., so they can help with this
question:
We're not supposed to help with homework here, and neither is
sci.stat.consult. However, since it is Christmas...
This looks like a pen-and-paper (theory) exercise, not an R one. Are
you sure that the R requirement is not intended to apply to
exercises further down the list? You might use expand.grid() to
find the elements of the powerset, but I'm not sure that actually
helps understanding.
Exercise 1. Let Ω = {H,T,E}(a set with 3 elements, called H ,T and
E . You
can think of “heads”, “tails” and “edge” if you like,
but this
interpretation is not necessary).
1. List the elements of the powerset P (Ω) of Ω. (Recall that the
powerset
of a set is the set of all subsets of that set, including Ø (the
empty set)
and the whole set.)
I don't think I'm violating the no homework rule too much by pointing
our that there is a powerset() function in the sets package. Why one
wouldn't do this one in their head is a bit beyond me, but if it's
really true that these need to be done in R, then maybe the author's
intent ti to get that package installed and loaded?
2. Suppose P is a set function on Ω (that is, a rule assigning real
numbers
to subsets of Ω). Suppose that
P({H,T}) = 3, P({H,E}) = 3, P({H}) = 1 444
Why is it impossible that P is a probability measure ? (That is, no
matter
how P is defined on the remaining subsets of Ω, it can’t be a
probability
measure.)
--
Best,
Matilda Gogos
matildaelizabe...@gmail.com
David Winsemius, MD
West Hartford, CT
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