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 QNT Classification

QNT classification scheme presents a new approach to the construction of general persistent polyhierarchical classifications.

By polyhierarchy we mean a set of categories partially ordered by relation "is a" where every element can have more than one parent (a non-tree hierarchy).

QNT classification is based on implicit description of category polyhierarchy by a compact generating polyhierarchy of classification criteria. Similarly to existing approaches, the classification categories are defined by logical functions encoded by attributive expressions. But unlike other methods, our classification technique provides inherently flexible definition of domains of criteria applicability, and the semantics of relations between categories is invariant to changes in the universe composition, extending variety of criteria and increasing their cardinalities.

To view a Powerpoint presentation outlining the approach and its benefits, click here (824 Kb).

A formal description of the QNT classification scheme has been published at arxiv.org.

To read a comprehensive popular description, click here.


ExLAF77 is an extended precision general purpose mathematical library for applications that require error free and/or variable precision floating point computations.
Product highlights:
  • unlimited* precision, unlimited* range of values in numerical operations with numbers, vectors and matrices of all types, including complex linear algebra operations
    * up to 231bits (256 Mbytes), or approximately 500 million decimal digits for any of: integer number, mantissa of floating-point number, exponent of floating-point number, numerator of rational number, denominator of rational number

  • total and automatic control of computational anomalies, guaranteed veracity of result for any valid input

  • requested bit accuracy of result is guaranteed for all values of argument of mathematical functions

  • higly abstracted hierarchy of types with mathematically rigorous and systematic classification of numerical objects

  • simple Fortran-77 programming interface - also callable from C as well as other languages compatible with Fortran

  • great flexibility of input/output operations
Sounds good?
Read more about ExLAF77!

What's new:

QNT classification scheme is presented at the IASTED International Conference 2004 in Innsbruck.

Now QNT classification scheme is described in the comprehensive popular form, click here.

Current versions:
ExLAF77 1.02
© 2002 QNT Software Dev. Inc.