Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.programming > #5766
| From | bartekltg <bartek@gmail.com> |
|---|---|
| Newsgroups | comp.programming |
| Subject | Re: Researches in quantum computing seem to progress only extremely slowly |
| Date | 2015-09-03 02:51 +0200 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <ms85il$ur$1@speranza.aioe.org> (permalink) |
| References | (12 earlier) <ms7vnf$rd$1@news.albasani.net> <ms80a0$nte$1@speranza.aioe.org> <ms80n3$28p$1@news.albasani.net> <ms82jv$rqr$1@speranza.aioe.org> <ms83rh$2tp$3@news.albasani.net> |
On 03.09.2015 02:22, Mok-Kong Shen wrote:
> Am 03.09.2015 um 02:01 schrieb bartekltg:
>> On 03.09.2015 01:28, Mok-Kong Shen wrote:
>>> Am 03.09.2015 um 01:21 schrieb bartekltg:
>>
>>>>
>>>>
>>>> This is exactly the answer to you question about 'mean entropy'.
>>>> You did not understand the direct answer because you do not
>>>> know math about entropy. This is why I also wrote the second
>>>> post about simplified problem, but with the same question
>>>> and answer.
>>>>
>>>> If I have a candy in one hand I do not have a half of bits
>>>> of enthropy in each hand. I have one bit in left and one
>>>> bit in right. But both bits are corelated, so if you
>>>> known one, you also known the second - second hand
>>>> have zero entropy, because ("under the assuption the
>>>> first hand in known") you known where the candy is.
>>>>
>>>> "Mean entropy" as you proposed ("128/n") have no sense,
>>>> because probability doesn't work that way.
>>>
>>> Ok, then simply entropy. Lets say that the 128 input bits
>>> are all of full entropy, each bit has entropy of 1.0. We
>>> assume that AES is very well designed such that the output
>>> n bits are equally good. How much entropy has under this
>>> assumption one output bit?
>>
>> One bit.
>> If AES is good, both 0 and 1 is equally probable,
>> so entropy is
>> -1/2*log(1/2) -1/2*log(1/2) = 1
>>
>>
>> Entropy of two bits is almost two.
>>
>> Entropy of the whole n bits is not greater than 128bits
>> //forth dot
>> https://en.wikipedia.org/wiki/Entropy_(information_theory)#Further_properties
>>
>
> So, assuming that the n bits are equally good, the entropy
> of each output bit is not greater than 128/n. A trivial
> calculation, isn't it?
No. You still don't get this hands and a candy story ;]
We have two bit random sequence.
00, 01, 10, 11, all with probability 1/4.
AES_2_4 generate:
AES(00) = 1011
AES(01) = 1000
AES(10) = 0111
AES(11) = 0110
[you can write better "AES" bunction and recalculate entropies]
Do you know definition of entropy?
x_i are possible sequewnces. P(x_i) propability od that seqence.
entropy H = \sum_i P(x_i)*log2(1/P(x_i))
Entropy of first bit is 1
Entropy of second bit is 1
entropy of third bit is 1/4log2(4) + 3/4log2(4/3) = 0.81128
entropy of fourth bit is 1
Entropy of first two bits?
We have only two possible sequences. 01 and 10.
Both have probability 1/2. So H = 1
First two bits have only one bit of entropy.
-How, first bit have one bit, and second bit have one bit,
this is total two bits!
look at the sequences. If I look at first bit and it is 1,
i know random sequieince was eithier 00 or 01.
But if I look at the second bit, I will not get any new information,
i knew before tjat second bit is NOT first bit.
First bit carry information, second bit carry information,
but this is the same information.
Second and third bit can be: 00, 01, 11. The last
with propability 1/2, first two - 1/4. H = 1.3466
The first and the last bit:
sequences:
11 10 01 00. propability od any =1/4. H=2.
If I look at these two bits, I can decipher whole sequence.
They carry whole information. If I know that, the rest of
the sequence have no more information for me.
Entropy of whole sequence is... of course 2 bits,
beceuse i have 4 possible sequences, echch with 1/4 chance.
bartekltg
Back to comp.programming | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-01 13:09 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-01 14:23 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-01 20:00 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-01 18:43 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 10:48 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-02 13:00 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 22:50 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-02 21:31 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 23:46 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-02 21:58 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 00:13 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-03 00:32 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:47 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 16:52 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 00:03 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 17:18 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 00:28 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 17:52 -0500
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 01:04 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 18:29 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 01:04 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 18:25 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 01:33 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 18:53 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:16 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:18 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 02:33 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:42 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 02:55 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 03:03 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 03:14 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 03:17 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 03:30 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 03:36 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 04:13 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 04:19 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 04:32 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 22:51 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 16:51 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-03 10:49 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-04 19:47 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-04 13:42 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-04 21:50 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-04 20:33 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-04 23:45 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-05 01:24 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 00:50 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-07 14:14 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-07 15:57 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-07 12:19 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-08 23:47 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-09 02:28 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-04 20:23 +0000
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-05 00:55 +0200
Re: Researches in quantum computing seem to progress only extremely slowly "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-09-04 17:11 -0700
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-05 02:31 +0200
Re: Researches in quantum computing seem to progress only extremely slowly "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-09-04 20:15 -0700
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 00:35 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 00:42 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 00:46 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 00:54 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 01:11 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 01:21 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 01:28 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 02:01 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:22 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 02:51 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 02:57 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 03:08 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 03:31 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 03:45 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 03:54 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 04:18 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-03 04:24 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Johannes Bauer <dfnsonfsduifb@gmx.de> - 2015-09-03 07:23 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 16:14 -0500
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 23:23 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Kaz Kylheku <kaz@kylheku.com> - 2015-09-02 21:33 +0000
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 23:54 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-02 23:22 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 23:32 +0200
Re: Researches in quantum computing seem to progress only extremely slowly bartekltg <bartek@gmail.com> - 2015-09-03 00:22 +0200
Re: Researches in quantum computing seem to progress only extremely slowly "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-09-01 13:23 -0700
Re: Researches in quantum computing seem to progress only extremely slowly Mok-Kong Shen <mok-kong.shen@t-online.de> - 2015-09-02 11:04 +0200
Re: Researches in quantum computing seem to progress only extremely slowly Robert Wessel <robertwessel2@yahoo.com> - 2015-09-02 02:22 -0500
csiph-web