This release of SDML provides some fairly extensive optimisations,
which should speed up existing simulations.

Additionally, the "sole" feature of syntax diagrams has been extended
so that it is utilised even if some arguments are not defined as
sole. Such predicates are known as "partially sole". [However,
predicates are only partially sole if they have a single forward
chaining clause definition, whose syntax diagram ensures that clauses
are of a fixed size, have sole arguments in fixed positions and have
ground terms as all arguments.] The non-sole arguments are treated as
an index, and the syntax diagram specifies that there is only one
value of each sole argument for the same index (at any particular
time for the same agent). An error results if it is attempted to
assert mutiple values for the same index. This feature is likely to
aid efficiency, because when such clauses are retrieved, typically
all of the index arguments are known before retrieval, enabling the
look-up to be performed quickly. For other predicates, indexing is
only done for the first argument; for partially sole predicates,
indexing is done for all non-sole arguments irrespective of their
position.

A further optimisation of partially sole predicates occurs when there
are two or three non-sole arguments, each of which is defined to be
an Integer. All clauses for such a predicate (at any particular time
for the same agent) are represented internally as a two or
three-dimensional grid, with coordinates starting at zero. This
enables retrievals to be performed particularly efficiently if any or
all of the index arguments are known before retrieval. [There is a
minor caveat: there must be at least four clauses and the grid must
be at least 5% full for SDML to choose a grid representation.
However, if a grid representation is used at one time period, it will
also be used at the next time period; SDML utilises the heuristic
that grids will typically remain the same size over time.]

This release of SDML also introduces a new tool - the profiler. The
profiler displays statistics about the amount of time spent firing
particular rules and performing other tasks during a simulation run.
A profiler window (provided using the navigator) can be opened using
the "open profiler" option in the "Browse" pull-down menu of the
workbench browser. The profiler can be started from this window or
when asked at the start of a simulation.

The obsolete clause repositories of databases have been improved to
include clauses involving undefined objects, due to an object
definition being removed. The clauses are moved back into the
database itself if the object definition is added again (perhaps due
to the operation being undone). A similar facility is now implemented
for obsolete rules that have been asserted into agents' content
rulebases by meta-agents. The obsolete rules can be browsed using the
navigator (but not the old-style browser) - they appear in the list
of meta-accessible rules with "++ obsolete rule ++" before their rule
names.