ANN: Dogelog Player 2.1.1 (Sky Limit)

Dear All,

We are happy to announce a new edition of the Dogelog Player:

- Enhanced GC:
To lift the native stack limitations, we opted for a marking algorithm based on Peter Deutschs algorithm E as found in Donald Knuths "The Art of Computing Programming" book. Our variant uses an int field that was anyway recently introduced for Prolog compound coloring, so that no extra space was introduced in this release.

- Enhanced Binary-Ops:
By adopting the pointer approach from Jaffar's Unification we could get rid of the map based realization from previous releases for union find. It turns out this gives quite a speed advantage. We also lifted the native stack limitation by using an extra space in the form of a stack and a log, which surprisingly performs well especially for Java, less for JavaScript and Python.

- Enhanced Unary-Ops:
For unary operations such as term_variables/2, ground/1, etc.. we experimented with both Peter Deutsch and a stack / log approaches. Interestingly for performance reasons we had to dismiss the two phase approach induced by a marking algorithm such as Peter Deutsch, and went also with the one phase approach as offered by a stack / log realization.

Have Fun!