T	the formula is true in the world
F	the formula is false in the world
U	the formula contains free variables that are undefined in the world
?	the formula contains a syntax error

Saving files:

For security reasons, the operations "Save as" and "Open" are not permitted for a Java Applet. In order to save and load worlds and formulas you have to download the Java archive blockworld.jar and then start the application on your computer by double clicking the icon or using one of the following commands:
java -jar blockworld.jar
java -classpath blockworld.jar ch.ethz.inf.rs.BlockWorld

Disclaimer: This program was written by Dr. Robert F. Stärk and is available here with his permission. It was inspired by a similar and more sophisticated commercial program called Tarski's World published by CSLI at Stanford University. The Block World available from this page is not the product of CSLI. Dr. Stärk is not affiliated with CSLI.