In Mathematica 6 there is an entry in the Cell menu: Notebook History.
Does it do anything apart from tracking the modification times of cells?
  Is anyone here using this feature?  If yes, how do you use it/why do
you find it useful?

I am just curious about this new feature.

Szabolcs

On Jun 13, 2007, at 6:31 AM , Szabolcs wrote:

I know I used it once to see how long a bug had been in a notebook,  
but I don't remember the details, other than the time period involved  
spanned a few months.

It will also tell you how many cells are in the notebook (or  
selection) and what their sizes are, which I sometimes find useful.

Brett Champion
Wolfram Research

I'm using it experimentally to replicate (part of) the effect of using a
time-stamped "laboratory notebook".

The time-honoured way to time stamp material (e.g. for patent priority
purposes) is to keep a countersigned paper record, but this doesn't work if
you do everything in electronic form (e.g. Mathematica notebooks) unless you
use some additional procedures to generate verifiable time stamps.

The Notebook History feature looks to me like a first attempt to generate
time stamps for Mathematica notebooks. It doesn't go all the way because you
can't determine the exact state of a notebook at a given point in the past,
but at least it shows where you have been going back to "fiddle" with
earlier results, and thus gives a last-updated time for each cell. As for
whether this sort of time stamp would be recognised in law, that presumably
would depend on whether the time stamps were difficult to fake. I think that
time-stamped copies of your notebooks are the only convincing approach here.

My "laboratory notebook" has been a web of Mathematica notebooks since
version 3.0, and up until now I have carefully added date labels to every
group of cells that I create and/or edit, AND I periodically make a
time-stamped copy of active notebooks. I don't yet know the precise way in
which I will end up using the new Notebook History feature; at the moment I
regard it as an experimental feature.

Steve Luttrell
West Malvern, UK

news:f4olfq$763$1@smc.vnet.net...

There are a variety of uses for this feature.  One simply is that is
showcases a number of FrontEnd technologies at work since it is built
entirely with top level Mathematica code.

Internal to the notebook cells have the option CellChangeTimes (as
long as the notebook has the option Track CellChangeTimes->True which
is the default).  And it is these data that are used to track the
notebook's evolving state.

When a notebook gets very large though the Notebook History notebook
has a hard time keeping up with the current state of the notebook. For
this reason, it might not be as useful without the addition of a means
to turn off its Dynamic updating and only display the notebook's state
when specifically asked by the user.  I think that this would
generally be a better default state (or something like this).

I agree that use of this as a means of verifying Intellectual property
creation might be useful.  But I don't belive that the US Patent
Office yet recognizes any electronic means of date stamping material.
However, I suspect that it could still be used in some fashion along
traditional countersigned with print outs of the material.

In A WorkLIfe FrameWork Diaries are tagged automatically as to when
they were modified (even in Mathematica version 5.x) and one of the
intentions of this was to be able to use them as laboratory
notebooks.  But a broader intention is that it allows me to locate
cells by their tags (I use CellTags rather than CellChangeTimes
because it allows me to associate a variety of dates with the cell and
its content).

Also in A WorkLIfe FrameWork Diaries there has been a facility similar
to the V6 Notebook History menu item in A WorkLIfe FrameWork's
Analytics Palette:

http://scientificarts.com/worklife/documentation/analyticspalette.html

In fact, this was the possible origin of the  V6 Notebook History menu
item.

An example of my use of this is to see when I have interacted with a
particular WorkLife FrameWork Diary or Notebook.  If the Diary is one
that I have created to keep items associated with a particular client,
for example, then this allows me to see at a glance when I worked on
things having to do with that client.

Also, once when I was looking at the history of the notebook that I
was writing the code for A WorkLIfe FrameWork  in (and autosave
package), I noticed that there was a big gap in when I added new
material to the notebook.  I wondered about this and then realized
that that was the time interval during which I was writing the
documentation.

So, things like this are one sort of tool for mining one's personal
data.

It is important to remember and realize that Mathematica is not just a
technical computation tool in the traditional sense, it is a System.
And within the system one can make tools that extend considerably
beyond the conventional.  I wanted to catalyze new directions in this
by creating A WorkLIfe FrameWork...

Tagging of all sorts is a very powerful way to work within a notebook
and to selectively locate and extract content.

see

http://scientificarts.com/worklife/documentation/taggingpalette.html

and

http://scientificarts.com/worklife/screencasts/tagging.mov

I hope that some of this helps...

--David

On Jun 15, 5:09 am, "Steve Luttrell"

Why not use a revision control system like Subversion? Space
constraints? Also, there is at least one system--git--that computes
the SHA1 hash of its entire repository history for each revision,
which would help in validating repository authenticity.

On 6/15/07, Steve Luttrell <steve@_removemefirst_luttrell.org.uk> wrote:

--
http://chris.chiasson.name/