Derivation of algorithmic control structures in Event-B refinement

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • Introducing an approach for making the control flow in Event-B explicit. • The approach augments Event-B with a scheduling language for specifying the control flow. • A number of refinement patterns for refining a schedule to a concrete level are introduced. • The correctness of the control flow is verified by removing the original guards from events in a schedule. • The approach is applied to the famous Schorr-Waite algorithm.

Formalising the Hybrid ERTMS Level 3 specification in iUML-B and Event-B

“…Based on this, we decided to use a new experimental tool called SEB-CG [25] for providing some suggestions on how we can derive code from our abstract model. SEB-CG implements the ideas presented in [26] and [27] where Event-B models are augmented with a schedule. The schedule makes the control flow between events explicit from the abstract level by allowing schedule refinement along with the Event-B refinement.…”

Verifiable Code Generation from Scheduled Event-B Models

“…The lack of explicit control flow in Event-B can make algorithm and sequential program development difficult. To deal with the problem of control flow, in our previous work we introduced Scheduled Event-B (SEB) [6]. SEB augments Event-B with an explicit control flow construct called a schedule.…”

“…Non-deterministic choices and iterations can be refined to deterministic branches and loops, respectively. Schedule refinement rules are defined in [6]. Figure 2 depicts how a schedule is refined alongside with the Event-B model.…”

“…Figure 2 depicts how a schedule is refined alongside with the Event-B model. To illustrate scheduled Event-B, we use the binary search algorithm presented in [6] here. We only provide the most concrete Event-B model of the search algorithm:…”

“…sequential program development) remains underdeveloped and not always easy to follow. In our previous work [6] we introduced Scheduled Event-B (SEB). SEB augments Event-B with a scheduling language and provides a number of refinement rules to facilitate derivation of algorithmic structure in Event-B refinement.…”