An Introduction to Requirements Capture Using PVS: Specification of a Simple Autopilot

This paper presents an introduction to capturing software requirements in the PVS formal language. The object of study is a simplified digital autopilot that was motivated in part by the mode control panel of NASA Langley''s Boeing 737 research aircraft. The paper first presents the requirements for this autopilot in English and then steps the reader through a translation of these requirements into formal mathematics. Along the way deficiencies in the English specification are noted and repaired. Once completed, the formal PVS requirement is analyzed using the PVS theorem prover and shown to maintain an invariant over its state space.

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