Brendan Leber wrote: > First, let me apologize for my extremely late reply. Right after I > started receiving replies I suffered some pretty serious system > failures. I'm now back and replying to old messages. B > > > On Mar 2, 2006, at 9:20 AM, Eric Wilhelm wrote: > > > It sounds like this usage is part of the foundation (if not "base") > > class Math::Interval which Brendan will need even though he might not > > be working directly on those bits. > > Yes, the foundation of the class will have functions that support > traditional interval functions such as overlap() and intersect().
Out of curiosity, is there a common agreement on these 'traditional interval functions'? The most referenced proposal I'm aware of are the so called Allen relations: Maintaining Knowledge about Temporal Intervals by James F. Allen They are - as the title suggests - somewhat biased towards temporal types (e.g. relation 'during'). A perl implementation is done in Date::Interval: <http://search.cpan.org/~ktorp/Interval.0.03/Interval.pm> Although the book Temporal Data and the Relational Model by C.J. Date, Hugh Darwen, Nikos Lorentzos <http://books.google.com/books?ie=UTF-8&vid=ISBN1558608559&id=grTubz0fjSEC&pg=PA91&lpg=PA91&l&sig=PQpCSlzWNl_uS66gfX3Lw2RK-WY> is also biased towards temporal types, the authors generalized the interval type: it's a type generator parameterized by a point type. By the way, 'during' was renamed to 'includes'. I have to admit I like their proposal. Are there other essential sources worth to consider? Steffen Goeldner
