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- April, 10th 2012
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
- March, 23 2010
Yet another piece of logic software:
Peirce's Alpha Graphs,
a free program for converting expressions of propositional logic to
Peirce's cool Existential Graphs.
- March, 17 2010
A new piece of logic software: Truth
Tables for Symbian devices (Nokia mobile phones)
- Some while ago
Gee, I completely failed to mention my
Truth Table Dashboard Widget
for MacOS X! It is completely free, but I would appreciate if you
would use the donation link conveniently placed on the download page.
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 It has been replaced by an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
- December, 28th 2006
Proof Builder that is part of the
Gateway to Logic
now supports defining connectives (see also the
Mathematica-style version of the Axiomatic Proof Builder).
- August, 12nd 2006
There is an axiomatic
(Hilbert-style) proof builder for propositional logic.
- January, 11th 2006
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 (firstname.lastname@example.org).
- 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.
- March, 28th 2005
Lemmon-style Proof Builder
and the Fitch-style Proof
Builder offer the following two features:
It was Ole Koksvik who proposed this useful feature.
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.
- September, 3rd 2002
The server side of the
Gateway to Logic now supports
conjunctive normal forms (CNF and CCNF).
- August, 10th 2002
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.
- August, 31st 1999
In addition to the Lemmon
style proof builder, the
Gateway to Logic now contains
a Fitch style proof
builder restricted to propositional logic.
- August, 31st 1999
Due to many requests from users of the
Gateway to Logic, I have
committed myself to the following statement
of year 2000 compliance.
- April, 12th 1999
The server side
of the Gateway to Logic
now offers graphical expression trees without requiring Java support on
the client side.
- March, 6th 1999
The Quine-McCluskey optimizer of my
Gateway to Logic is now
available in two versions, one of them accepting partial truth tables,
the other accepting plain propositions of propositional logic.
- March, 5th 1999
The Logic Server has entered into diplomatic relations
with the Planet of Sheep!
- February, 25th 1999
The Proof Builder of the
Gateway to Logic now supports
lemmas and their application. There will be some documentation in the
- February, 1st 1999
My Gateway to Logic
now also offers Quine-McCluskey
- January, 26th 1999
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
- November, 9th 1998
The Gateway to Logic was
Key Resource - Logic Topic
- June, 13th 1998
From now on, you can reach me via
ICQ, number 14014915.
- May, 28th 1998
The server side of my
Gateway to Logic now offers
a new function to check propositions for their intuitionistic validity.
- January, 29th 1998
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.
- August, 16th 1997
A detailed server statistics page is available.