Probably due to a compiler bug triggered by a recent change (no joking!), the
functions of the Gateway to Logic stopped computing conjunctive
normal forms (CNFs). Many thanks to Elías F. Combarro who noticed, and made
me aware of the problem.
It became necessary to change a hard disk of the Logic Server. I found
this a welcome opportunity for updating the Linux distribution used.
As a side-effect of the configuration works done, there is now an HTTPS
server running, too.
February, 25 2011
Truth Tables for Android - due to the much more powerful
Android platform, this version is highly improved over its recent counterparts,
e.g. supporting, besides classical logic, a number of non-classic, multi-valued
Nothing happened in 2009. Maybe more things happened in
May, 5th 2008
functions of the Gateway to Logic now provide an optimizer
suitable for dealing with canonical normal forms. In general, this
leads to shorter CNFs than in the past.
January, 9th 2008
After more than eight years of service, the venerable Celeron 366
hardware of the Logic Server was retired. It has been replaced by an
up-to-date new computing device that covers less space than a paperback,
is much more environmentally friendly by consuming only
0,1-10 Watt per hour (depending on system load), and, most important,
whose exterior is of truly splendid yellow colour.
Nothing happened in 2007. Maybe more things happened in
Today n such that n is the number of bugs of the
Peirce Alpha Graph Proof
Builder has been decreased by one. From now on, it is also possible
directly to apply the rule of Iteration to a negation, meaning that
it is no longer impossible to derive the valid argument
January, 8th 2006
Thanks to a hint from Jon Merzel, two bugs in the
Lemmon-style Proof Builder have
been eliminated: vI now quotes the right line number (i.e. without incrementing
it by 1), and vE more carefully checks the dependencies within the
September, 1st 2005
There are ongoing attempts to restructure the web pages at the Logic
Server. This may lead to temporary inconsistencies, missing pages,
dangling links and so on. If you experience any problem, please
let me know (email@example.com).
August, 14th 2005
Now the Gateway to Logic supports the logical system of Charles Sanders
Peirce, too: The Alpha Graph
Proof Builder has gone online today.
Copy & paste: If your Java subsystem is configured to allow applets
clipboard access, you may copy the proof to the clipboard
Print view: Even if your Java subsystem does not allow clipboard access,
you may copy the proof from the new "Print view" window by the copy &
paste feature of your operating system. If your browser is capable of
printing a window's content, you may as well directly print the proof.
It was Ole Koksvik who proposed this useful feature.
I have added another server
side function to the Gateway
to Logic. To a given proposition, the new function shows the
Begriffsschrift notation (i.e. the notation introduced by Gottlob Frege
in his 1879 "Begriffsschrift").
August, 3rd 2002
A new function has been added to the
Gateway to Logic. The new
server side function
graphically shows the alpha graph to a given proposition. Alpha graphs
are a notation devised by the American philosopher Charles Sanders Peirce.
The Computer Service Department of the Humanities which hosted my web
pages has been finally closed. For this reason the old URLs
"http://gewiwuerg.gew.univie.ac.at/~chris/" are not valid any longer. Please
be so kind to update your bookmarks and/or referring pages and to inform the
webmistress(es) and/or webmaster(s) responsible for the referring pages and/or
the persons responsible for informing the webmistress(es) and/or webmaster(s)
about changes to addresses to which their pages refer about this change.
November, 20th 1998
The new beta version of my program checking for
propositional intuitionistic validity is now part of the
server side of my
Gateway to Logic. An improved algorithm covers the whole of intuitionistic
logic. (The old algorithm was a bit faster, but sometimes covered not
I have set up a questionaire to get some ideas
on who is using my Gateway to Logic
and what problems they are experiencing. Please feel free to fill out the
form - you would be the fourteenth one to do so.