Performing Algorithmic Reenement before Data Reenement in B Performing Algorithmic Reenement before Data Reenement in B

Algorithmic Reenement is part of the theory of the B method both at the reenement and implementation stages. It a sign of how little loop introduction is used in practice at the reenement stage that neither the B-Toolkit nor Atelier-B provide support for loop introduction until the implementation stage. This paper examines the use of algorithmic reenement in general before data reenement. This involves extending the usual scope of data reenement which usually happens before algorithmic reenement. Two case studies are used to compare and contrast the application of algorithmic reenement before data reenement and vice versa. Some extensions are needed in the B-Toolkit to implement this style (i.e., algorithmic before data reenement) and are proposed. Some workarounds are also presented when appropriate.