IIRC, YOPY expected pricing has already
been announced, and is in the $500 range. I
expect that price to drop rapidly whether
or not YOPY is a success.
YOPY should be much cheaper than
the iPaq, for several reasons:
The biggest single cost component of the
iPaq is the display. While this reflective
high-contrast color LCD is wonderful, it adds
literally several hundred dollars to the price.
There is no WinCE license fee for
YOPY.
I've heard rumors that
the iPaq is a bit overbuilt to
make the WinCE port possible/easier, although
I have no details. This is obviously not
a problem for YOPY.
I'll seriously consider a YOPY once they're
actually available (not just pre-orderable).
HTTP is not stateless
in the same way that Gopher is. HTTP
includes header information transferred from client to server, which at least allows
the client to identify itself.
The Gopher UDP
``protocol'' has no facility for identifying
the client on the other end of the server: note that neither the IP address (which is non-unique) nor the UDP source
port (which the client may vary from request
to request) is sufficient for this task. Thus, the
only way to maintain session information in
the case that two clients are connecting from the
same box is to have each client virtually
connect to a different Gopher page! Needless
to say, this is not pretty...
Recall that Gopher's big ``efficiency win'' (and it wasn't that big in any case I ever saw) came largely from the fact that it is completely stateless. At the time, that was believed to be a good thing.
But stateless basically means sessionless. It was incredibly difficult to have restricted access
sites, per-user configuration, and the like, because there was by design absolutely no implicit or explicit connection possible between successive messages sent from a given client.
To be fair, sessions are hard even using HTTP. But it was much worse for Gopher. I, for one, was glad to see it go.
I'm a little confused. As I understood it, Quantum Electrodynamics and Quantum Chromodynamics already pretty much merge Special Relativity with Quantum Mechanics. Perhaps our protagonists are searching for a theory
which would merge General Relativity with Quantum Mechanics? But if so, why not just use the
standard name for such theories: Quantum Gravity?
I'm always suspicious of these kinds of books.
IMHO you should be required to have a Ph.D. in the field you're writing fiction about:-). ObStory: A FOAF served as the math consultant for Good Will Hunting. He got the job when he overheard some of the players in a bar talking about a character pursuing the Nobel Prize in Mathematics, and was kind enough to let them know about the problem.
OTOH, maybe a degree from the venerable Bob's School of Quantum Mechanics
would suffice...
Any chance the "Posted By" field of this article could read "Cmdr Taco" rather than "Jon Katz". As it stands, it looks like he's claiming his work is some of the most important ever posted on Slashdot:-).
I have to say that, based on this review, I can't imagine purchasing the book. Knowing Harel's reputation leads me to believe that the review is flawed.
Questions about the theoretical limits of computing are governed by three theses.
The Church-Turing-Tarski Thesis says that the computer on your desktop is roughly as powerful as any computer anyone could ever build.
The Polytime Thesis attempts to clarify ``roughly'' in the previous sentence. It claims that anything that can be done in polytime can be done in low-order polytime; to oversimplify, that things that are possible for a very powerful computer should be possible for yours if you're willing to wait just a little longer.
The third thesis is that "P is not equal to NP". Again very simplistically, this says that ``guessing right is lucky'': You cannot build a computer which solves problems quickly by always guessing right and then checking the guesses to be sure.
Without turning all three theses into theorems, the limits of computability remain fuzzy. Many, perhaps most, practically interesting computational problems appear to be NP-complete, and we are not yet certain whether these problems are inherently tractable.
As I said before, I'm sure Harel understands all this. Perhaps I'll try to browse a copy of his book at the local bookstore, and see what he really says.
Slashdot Mirror
IIRC, YOPY expected pricing has already been announced, and is in the $500 range. I expect that price to drop rapidly whether or not YOPY is a success.
YOPY should be much cheaper than the iPaq, for several reasons:
- The biggest single cost component of the
iPaq is the display. While this reflective
high-contrast color LCD is wonderful, it adds
literally several hundred dollars to the price.
- There is no WinCE license fee for
YOPY.
- I've heard rumors that
the iPaq is a bit overbuilt to
make the WinCE port possible/easier, although
I have no details. This is obviously not
a problem for YOPY.
I'll seriously consider a YOPY once they're actually available (not just pre-orderable).HTTP is not stateless in the same way that Gopher is. HTTP includes header information transferred from client to server, which at least allows the client to identify itself.
The Gopher UDP ``protocol'' has no facility for identifying the client on the other end of the server: note that neither the IP address (which is non-unique) nor the UDP source port (which the client may vary from request to request) is sufficient for this task. Thus, the only way to maintain session information in the case that two clients are connecting from the same box is to have each client virtually connect to a different Gopher page! Needless to say, this is not pretty...
Recall that Gopher's big ``efficiency win'' (and it wasn't that big in any case I ever saw) came largely from the fact that it is completely stateless. At the time, that was believed to be a good thing.
But stateless basically means sessionless. It was incredibly difficult to have restricted access sites, per-user configuration, and the like, because there was by design absolutely no implicit or explicit connection possible between successive messages sent from a given client.
To be fair, sessions are hard even using HTTP. But it was much worse for Gopher. I, for one, was glad to see it go.
Dang. Wrong link. Bob's School of Quantum Mechanics lives here, among other places.
I'm a little confused. As I understood it, Quantum Electrodynamics and Quantum Chromodynamics already pretty much merge Special Relativity with Quantum Mechanics. Perhaps our protagonists are searching for a theory which would merge General Relativity with Quantum Mechanics? But if so, why not just use the standard name for such theories: Quantum Gravity?
I'm always suspicious of these kinds of books. IMHO you should be required to have a Ph.D. in the field you're writing fiction about :-). ObStory: A FOAF served as the math consultant for Good Will Hunting. He got the job when he overheard some of the players in a bar talking about a character pursuing the Nobel Prize in Mathematics, and was kind enough to let them know about the problem.
OTOH, maybe a degree from the venerable Bob's School of Quantum Mechanics would suffice...
Any chance the "Posted By" field of this article could read "Cmdr Taco" rather than "Jon Katz". As it stands, it looks like he's claiming his work is some of the most important ever posted on Slashdot :-).
I have to say that, based on this review, I can't imagine purchasing the book. Knowing Harel's reputation leads me to believe that the review is flawed.
Questions about the theoretical limits of computing are governed by three theses. The Church-Turing-Tarski Thesis says that the computer on your desktop is roughly as powerful as any computer anyone could ever build.
The Polytime Thesis attempts to clarify ``roughly'' in the previous sentence. It claims that anything that can be done in polytime can be done in low-order polytime; to oversimplify, that things that are possible for a very powerful computer should be possible for yours if you're willing to wait just a little longer.
The third thesis is that "P is not equal to NP". Again very simplistically, this says that ``guessing right is lucky'': You cannot build a computer which solves problems quickly by always guessing right and then checking the guesses to be sure.
Without turning all three theses into theorems, the limits of computability remain fuzzy. Many, perhaps most, practically interesting computational problems appear to be NP-complete, and we are not yet certain whether these problems are inherently tractable.
As I said before, I'm sure Harel understands all this. Perhaps I'll try to browse a copy of his book at the local bookstore, and see what he really says.