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#126 Dark Discussions at Cafe Infinity » Religious discussion » 2013-06-14 23:25:59

phanthanhtom
Replies: 26

Get this straight. Discuss your religion. Find out the best.
For me atheism is better than any religion. Look at Scandinavia. Not many of them are religious, and result: Good statistics everywhere.
Not communism. Communism is forced atheism. Scandinavia is the example of voluntary atheism.

#127 Re: Help Me ! » Prime numbers » 2013-06-14 23:23:22

There might be an infinite number of solutions. I think so.
And there might be two pairs of the same numbers. Or a = b and c = d. As long as not all of them are the same. (In fact I acknowledge that that sentence is redundant)

#128 Re: Science HQ » Pluto » 2013-06-14 20:44:49

By now there are 5 satellites of Pluto.
Is there going to be more?

#129 Help Me ! » Prime numbers » 2013-06-14 20:38:51

phanthanhtom
Replies: 4

Find all sets of 4 different prime numbers (a, b, c, d) with

such that the sum of any three out of these four primes are also prime.
In other words, find positive integers a, b, c, d such that a, b, c, d, a+b+c, a+b+d, a+c+d and b+c+d are eight different primes.

#130 Re: Introductions » SPEM Life » 2013-06-14 20:22:02

I was a novice when I started this topic. I posted once in June 2012, and I was absent until two days ago when I posted my second post.

#133 Re: Help Me ! » Words for combinatorial maths » 2013-06-14 03:15:31

Again, I am looking for alternative names. I finished reading that twelvefold Wikipedia article. Formulae enough.

#134 Re: Help Me ! » Words for combinatorial maths » 2013-06-14 03:14:22

In other words, partial permutation <=> k < n

#136 Re: Introductions » SPEM Life » 2013-06-14 03:07:11

Anybody have any information on BIMC? I am looking for participation informations (i.e. which country participates).

#137 Re: Help Me ! » Words for combinatorial maths » 2013-06-14 03:05:03

Thank you. The Vietnamese names for them roughly translates to:
A. permutation
B. partial permutation
C. combination
D. partial permutation with repetition
E. combination with repetition
I am looking for formal and better alternatives, for I translate by my knowledge all these names, and it would be really important for BIMC.

#138 Re: Help Me ! » Words for combinatorial maths » 2013-06-14 01:06:31

Thanks, but I stress again that I need the official NAME, not the formulae.

#139 Introductions » SPEM Life » 2013-06-13 23:38:36

phanthanhtom
Replies: 9

That stands for the Four Pillars of My Life: Scandinavia, Politics, Eurovision, Mathematics.
And yes, I'm trying to turn on my signature. I added this 'four pillars' thing to the signature, but it doesn't work:(. Help me!
I am taking part in BIMC this July. Therefore, I look for helpers around here. I am 12 years old and will represent Vietnam at the Bulgarian International Mathematical Competition.
And I'd like if someone gives me a list of all BIMC countries/territories. According to the Scandinavia and Eurovision pillars, I'm looking for European (particularly Scandinavian) friends, and I'm glad if I found some of them in Bulgaria this July. Apart from Bulgarians, of course, for that is obvious.

#141 Re: Help Me ! » Words for combinatorial maths » 2013-06-13 03:49:32

For k=3, n=5:
a. (a1, a2, a3, a4, a5) and (a1, a3, a4, a2, a5) are different solutions. All solutions contains all 5 objects.
b. (a1, a2, a3), (a1, a2, a4), (a1, a3, a2) are different solutions. (a1, a1, a4) is not, for repetition not allowed.
c. (a1, a2, a3) and (a2, a3, a5) are different solutions. (a1, a2, a3) and (a2, a3, a1) are the same. (a1, a3, a3) is not a solution.
I'm afraid I would be away now because it's late. I'll be back GMT 8:00 am. So I look for the answers then.
And I only need the words. I'm sure I know the formulae, just I don't have enough time.

#142 Re: Help Me ! » Words for combinatorial maths » 2013-06-13 03:39:05

d. For example if k=5, then (a1, a2, a2, a3, a3) would be a solution (repetition allowed), and it would be different from, say, (a1, a2, a3, a2, a3).
e. The above 2 would be the same solution, as order doesn't matter.

#143 Re: Help Me ! » Words for combinatorial maths » 2013-06-13 03:30:17

What do you mean? I don't know the formula!

#144 Re: Help Me ! » Words for combinatorial maths » 2013-06-13 03:24:38

Given a set of n non-recurring objects,

, and a number k such that
. Find words that fit in the following definition.
a, A way of arranging all n objects (order matters, formula
).
b, A way of choosing AND arranging k out of the n objects (order matters, formula
)
c, A way of choosing k out of the n objects (order does NOT matters, formula
)
d, A way of choosing AND arranging k objects from S, repetition allowed, order matters.
e, A way of choosing k objects from S, repetition allowed, order does NOT matters.
Note: If not mentioned, repetition is not allowed.
P.S. Sorry for the older post, it's just an experiment. I forgot to put the formula tag in. Again, sorry.

#145 Help Me ! » Words for combinatorial maths » 2013-06-13 02:49:09

phanthanhtom
Replies: 20

I'm having trouble fitting words into the following definitions.
Given a set of n non-recurring objects, S = {a1, a2, a3, ..., an}, and a number k such that 0 <= k <= n. Find words that fit in the following definition.
a, A way of arranging all n objects (order matters, formula n!).
b, A way of choosing AND arranging k out of the n objects (order matters, formula n!/k!)
c, A way of choosing k out of the n objects (order does NOT matters, formula n!/k!(n-k)!)
d, A way of choosing AND arranging k objects from S, repetition allowed, order matters.
e, A way of choosing k objects from S, repetition allowed, order does NOT matters.
Note: If not mention, repetition is not allowed.
P.S. I have no experience using maths formula on this forum, so I prefer not to do so. But I hope I can learn how to do so.

#146 Re: Puzzles and Games » Can you suggest six names of great mathematicians quickly? » 2012-06-22 03:04:07

Carl F. Gauss
Leonhard Euler
Euclid
René Descartes
Fermat
Pythagoras
Newton should go to the nomination for best physicists. Most of his life spent on physics, not mathematics!

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