At present a handful of comparisons have been made of different variants of worked examples and tutored problem solving. There is some evidence to report a benefit of adding worked examples (WE) to current tutored problem solving (TPS) environments. Our research investigated how a “pure” WE condition could compete with a TPS condition. By pure we mean the WE condition does not include tutoring,...

Outer joins are extended relational algebra operations intended to deal with unknown information represented with null values. This work shows an approach to embed both null values and outer join operations in the deductive database system DES (Datalog Educational System), which uses Datalog as a query language. This system also supports SQL, where views and queries are compiled to Datalog prog...

An attack on the implementation of control vectors in the IBM Common Cryptographic Architecture is presented. The final key−part holder in a multiple part import introduces two key−encrypting keys (KEKs), one the intended key and one with a chosen difference from the former, by including this difference in his own key part. When this difference is set to the difference between two control vecto...