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Steps to an advanced Ada programming environment
Conceptual simplicity, tight coupling of tools, and effective support of host-target software development will characterize advanced Ada programming support environments. Several important principles have been demonstrated in the Arcturus system, including template-assisted Ada editing, command completion using Ada as a command language, and combining the advantages of interpretation and compliation. Other principles, relating to analysis, testing, and debugging of concurrent Ada programs, have appeared in other contexts. This paper discusses several of these topics, considers how they can be integrated, and argues for their inclusion in an environment appropriate for software development in the late 1980's
The Number of Hierarchical Orderings
An ordered set-partition (or preferential arrangement) of n labeled elements
represents a single ``hierarchy''; these are enumerated by the ordered Bell
numbers. In this note we determine the number of ``hierarchical orderings'' or
``societies'', where the n elements are first partitioned into m <= n subsets
and a hierarchy is specified for each subset. We also consider the unlabeled
case, where the ordered Bell numbers are replaced by the composition numbers.
If there is only a single hierarchy, we show that the average rank of an
element is asymptotic to n/(4 log 2) in the labeled case and to n/4 in the
unlabeled case.Comment: 7 page
Special Geometry and Twisted Moduli in Orbifold Theories with Continuous Wilson Lines
Target space duality symmetries, which acts on K\"ahler and continuous Wilson
line moduli, of a () 2-dimensional subspace of the moduli
space of orbifold compactification are modified to include twisted moduli.
These spaces described by the cosets are
K\"ahler, a fact which is exploited in deriving the extension of tree
level duality transformation to include higher orders of the twisted moduli.
Also, restrictions on these higher order terms are derived.Comment: 13 page
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