KnowledgeWorks and Prolog User Guide > 6 Advanced Topics > 6.2 Optimization > 6.2.3 Backward Chaining

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The KnowledgeWorks Backward Chainer supports the transformation of "tail-recursive" calls into jumps. Thus, stack overflow can be avoided without resorting to "repeat, fail" loops in most cases. For example, given the definition:

(defrule run-forever :backward

the call: (run-forever) will run forever without generating a stack overflow. Note that this optimization is not limited to recursive calls to the same rule. The last call of any rule will be compiled as a jump, drastically reducing stack usage.

KnowledgeWorks and Prolog User Guide (Unix version) - 22 Dec 2009