The Countdown Problem

Hutton, Graham

Abstract

We systematically develop a functional program that solves the countdown problem, a numbers game in which the aim is to construct arithmetic expressions satisfying certain constraints. Starting from a formal specification of the problem, we present a simple but inefficient program that solves the problem, and prove that this program is correct. We then use program fusion to calculate an equivalent but more efficient program, which is then further improved by exploiting arithmetic properties.

• Journal Article Type: Article
• Publication Date: Nov 1, 2002
• Journal: Journal of Functional Programming
• Print ISSN: 0956-7968
• Publisher: Cambridge University Press (CUP)
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 6
• APA6 Citation: Hutton, G. (2002). The Countdown Problem. Journal of Functional Programming, 12(6),
• Copyright Statement: Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf