BNR Prolog, also known as CLP(BNR), is a declarative constraint logic programming language based on relational interval arithmetic developed at Bell-Northern Research in the 1980s and 1990s. Embedding relational interval arithmetic in a logic programming language differs from other constraint logic programming (CLP) systems like CLP(R) or Prolog-III in that it does not perform any symbolic processing. BNR Prolog was the first such implementation of interval arithmetic in a logic programming language. Since the constraint propagation is performed on real interval values, it is possible to express and partially solve non-linear equations.
are expressed in CLP(BNR) as:
and a typical implementation's response would be:
<samp> X = _58::real(1.0966681287054703,1.0966681287054718),<br> Y = _106::real(1.9486710896099515,1.9486710896099542). <br> Yes<br> </samp>