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Author Topic:   The value of Gitt information
Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 16 of 24 (330519)
07-10-2006 4:24 PM
Reply to: Message 15 by Cal
07-10-2006 3:41 PM


For now, I'll offer this hint: I'm suggesting that DNA transcription is, ultimately, as deterministic a process as is a rock rolling down a hill.

I'm not sure it is transcription that is the relevant point when we are talking about the origin of the information within DNA, if there is any.

TTFN,

WK


This message is a reply to:
 Message 15 by Cal, posted 07-10-2006 3:41 PM Cal has not yet responded

    
Percy
Member
Posts: 18494
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.9


Message 17 of 24 (330532)
07-10-2006 4:50 PM
Reply to: Message 15 by Cal
07-10-2006 3:41 PM


Cal writes:

Well, if we want to be really pedantic, the strictest possible interpretation of Gitt might be said to include the implication that information (which cannot exist without a code, transmitter, etc) isn't actually information when it isn't being encoded, transmitted, or decoded. What it is the rest of the time, I can't imagine.

I wasn't saying anything about Gitt information. I don't know that a consistent and valid interpretation of it is possible - Gitt information seems to me just a bunch of unsupported assertions. The context of my reply was the encoding and decoding of Shannon information.

Actually, information is one of a set of messages that you wish to communicate.

Apologies for not finding that very... well, informative. "Wish" seems to be the key word there.

The principle that you find uninformative is at the core of Shannon information. This is from the 2nd paragraph of Shannon's original paper:

Shannon writes:

The significant aspect is that the actual message is one selected from a set of possible messages.

Moving on:

Cal writes:

I guess the whole metaphor must not have worked for you then. I don't have time to unpack it fully right now; maybe this evening. For now, I'll offer this hint: I'm suggesting that DNA transcription is, ultimately, as deterministic a process as is a rock rolling down a hill.

I think just your saying this clarifies your meaning, which at heart is about making an interpretation of which constitutes signal and which noise. But that involves assigning meaning, which as Shannon correctly states, is irrelevant to the engineering problem. Once you've made your choices about what constitutes signal and noise, then you can begin solving the information engineering problem.

--Percy


This message is a reply to:
 Message 15 by Cal, posted 07-10-2006 3:41 PM Cal has responded

Replies to this message:
 Message 18 by Cal, posted 07-11-2006 1:04 AM Percy has responded

    
Cal
Inactive Member


Message 18 of 24 (330690)
07-11-2006 1:04 AM
Reply to: Message 17 by Percy
07-10-2006 4:50 PM


WK writes:

I'm not sure it is transcription that is the relevant point when we are talking about the origin of the information within DNA, if there is any.


Agreed. Haste is my excuse. "Transcription and translation" would have been better.

Percy writes:

I wasn't saying anything about Gitt information.


Oh, sorry. I guess I let the thread's title lead me astray.

Percy writes:

The principle that you find uninformative is at the core of Shannon information.

[from the 2nd paragraph of Shannon's original paper]:
The significant aspect is that the actual message is one selected from a set of possible messages.

There's always going to be a teleological referent, which (again) is precisely my point. Here, it is the word: "selected". "As in natural selection?" (did I hear you say?) Yes, but remember, the term "natural selection" is a metaphor; no entity is required to make the choices, the choices make themselves. I stand by my claim that Shannon -- by the very act of explicitly excluding semantics from his model -- implicitly acknowledges the existence of some entity or entities with the capacity to find "meaning" (hopeless to define anyway) in symbols. If I axed you to relay a message for me, and it contained sum miss pelled words, would you have a reilable way of knowing whether those apparunt errors were kritical to the meaning of the "aksuall message"?

Percy writes:


I think just your saying this clarifies your meaning, which at heart is about making an interpretation of which constitutes signal and which noise. But that involves assigning meaning, which as Shannon correctly states, is irrelevant to the engineering problem. Once you've made your choices about what constitutes signal and noise, then you can begin solving the information engineering problem.


Meaning isn't merely irrelevant to Shannon's purpose. It is assumed that among the set of all possible messages exists one which is the most meaningful, but it is not only unnecessary to choose between them on that basis, it is absolutely imperative that no attempt be made to do so; the message must be considered to have been at its maximum fidelity at the signal end.

Edited by Cal, : No reason given.


This message is a reply to:
 Message 17 by Percy, posted 07-10-2006 4:50 PM Percy has responded

Replies to this message:
 Message 19 by Percy, posted 07-11-2006 3:28 AM Cal has not yet responded
 Message 21 by Wounded King, posted 07-11-2006 4:40 AM Cal has not yet responded
 Message 22 by Percy, posted 07-11-2006 4:59 AM Cal has not yet responded

  
Percy
Member
Posts: 18494
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.9


Message 19 of 24 (330700)
07-11-2006 3:28 AM
Reply to: Message 18 by Cal
07-11-2006 1:04 AM


Cal writes:

Percy writes:

I wasn't saying anything about Gitt information.

Oh, sorry. I guess I let the thread's title lead me astray.

Well, now I'm confused. Are you saying that when you wrote this in Message 13:

Cal in Message 13 writes:

My problem is in the circular way "information" is defined:

What is a code? That which contains information.
What is information? That which is represented by a code.
What is DNA? Coded information.

That you were talking about a problem with Gitt information, not Shannon information? It was written in response to a paragraph from WK about Shannon information.

If I axed you to relay a message for me, and it contained sum miss pelled words, would you have a reilable way of knowing whether those apparunt errors were kritical to the meaning of the "aksuall message"?

Yes, of course, but that's because of redundancy. The correct letters are only one of the many cues for the correct information.

Meaning isn't merely irrelevant to Shannon's purpose. It is assumed that among the set of all possible messages exists one which is the most meaningful,...

No, this is not assumed. As Shannon correctly states, meaning is irrelevant to the engineering problem.

...but it is not only unnecessary to choose between them on that basis, it is absolutely imperative that no attempt be made to do so; the message must be considered to have been at its maximum fidelity at the signal end.

My guess is that you're making the mistake of thinking that communicating information in the presence of noise is somehow associated with meaning. If an encoding of information contains insufficient redundancy such that after transmission through a noisy medium it is ambiguous which message from the set was originally sent, selecting a message from the set based upon some criteria is not an exercise where meaning has any role.

--Percy


This message is a reply to:
 Message 18 by Cal, posted 07-11-2006 1:04 AM Cal has not yet responded

Replies to this message:
 Message 20 by Wounded King, posted 07-11-2006 4:36 AM Percy has not yet responded

    
Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 20 of 24 (330704)
07-11-2006 4:36 AM
Reply to: Message 19 by Percy
07-11-2006 3:28 AM


Cal writes:

I stand by my claim that Shannon -- by the very act of explicitly excluding semantics from his model -- implicitly acknowledges the existence of some entity or entities with the capacity to find "meaning" (hopeless to define anyway) in symbols.

But that isn't what you claimed, you claimed that Shannon made ...

Cal writes:

... the tacit assumption that the message originated with an intelligent source

which is quite distinct from acknowledging that entities exist which can ascribe meaning to symbols. After all the reciever alone can ascribe meaning to the symbols they receive, and I might suggest that is what is happening in this case. We can find shannon information in DNA but the meaning we attach to it is our own interpretation and understanding of its physico-chemical function. And if we remove the neccessity for intelligence at the source then natural selection is a perfectly valid mechanism for 'selecting' a specific message from all the possible messages.

TTFN,

WK

Edited by Wounded King, : No reason given.


This message is a reply to:
 Message 19 by Percy, posted 07-11-2006 3:28 AM Percy has not yet responded

    
Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 21 of 24 (330705)
07-11-2006 4:40 AM
Reply to: Message 18 by Cal
07-11-2006 1:04 AM


Agreed. Haste is my excuse. "Transcription and translation" would have been better.

Again I would disagree. Transcription and translation are the appropriate stages if we are looking at the transmission of information from the genome being used to 'inform' the synthesis of proteins but not if we are interested in the origin of the information in the genome itself. For that we surely have to look at mutation and natural selection.

TTFN,

WK


This message is a reply to:
 Message 18 by Cal, posted 07-11-2006 1:04 AM Cal has not yet responded

    
Percy
Member
Posts: 18494
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.9


Message 22 of 24 (330706)
07-11-2006 4:59 AM
Reply to: Message 18 by Cal
07-11-2006 1:04 AM


I think Message 20 from WK was intended as a response to you, not me.

--Percy


This message is a reply to:
 Message 18 by Cal, posted 07-11-2006 1:04 AM Cal has not yet responded

Replies to this message:
 Message 23 by Wounded King, posted 07-11-2006 5:07 AM Percy has not yet responded

    
Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 23 of 24 (330707)
07-11-2006 5:07 AM
Reply to: Message 22 by Percy
07-11-2006 4:59 AM


Oops, sorry Percy.

TTFN,

WK

Edited by Wounded King, : No reason given.


This message is a reply to:
 Message 22 by Percy, posted 07-11-2006 4:59 AM Percy has not yet responded

    
Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 24 of 24 (531844)
10-20-2009 7:48 AM


*Bump*
Just to bring this up again since the topic has arisen in Ned's thread.

TTFN,

WK


    
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