| Thread Links | Date Links | ||||
|---|---|---|---|---|---|
| Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
Nate Hayes wrote:
Arnold Neumaier wrote:Michel Hack wrote:I vote YES on Motion 13.04 -- seven standardized interval comparators. This is a good compromise. Three may be theoretically sufficient, but implementations are likely to provide more, and it would be a shame is this resulted in a mess of similar but not identical operations.Motion 13.04 says in the abstract: ''the number of comparison relations defined by the standard should be kept to a minimum.'' But Motion 13.04 provides only 1/3rd of the necessary comparisons, and only 1/7th of the comparisons provided are necessary. Thus the motion is self-contradictory. Motion 13.04 requires 7 transitive relations, only the second of which is actually useful. The interior relation (the fifth) is not the topological one, and hence will only cause confusion. Two relations disjoint interior(topological) -- both very important in practice -- are missing, Thus Motion 13.04 is _not_ a compromise, but something quite different from my proposal.The disjoint relation is most efficiently implemented in hardware and software in terms of the "preceding" relation in Motion 13.04:disjoint(A,B) = ( A \prec B ) or ( B \prec A)This can even be computed in a single overlapping operation (Motion 21). IMHO, your argument that disjoint is an important relation is therefore evidence "preceding" is one of the relations P1788 must standardize.
I rather regard your observation as a further argument against the motion, since it invites inefficient solutions: Your proposal replaces a single interval operation that is easy to implement (with 2 real compares and 1 logical and) by two interval operations and a logical and (requiring in total 4 real compares, 2 logical ands and one logical or), and overhead of almost a factor of two. Surely, such easily avoidable kinds of inefficiency should not be a hallmark of the future standard. Arnold Neumaier