Yeah, common in the Constraint-based, or Logic, Programming paradigm. This particular spec was established in Greg Badros & Alan Borning's Constraint CSS (CCSS

Yeah, common in the Constraint-based, or Logic, Programming paradigm. This particular spec was established in Greg Badros & Alan Borning's Constraint CSS (CCSS): https://www.cs.washington.edu/research/constraints/web/ccss-uwtr.pdf https://www.cs.washington.edu/research/constraints/web/ccss-...