Abstract Hliněný’s Theorem shows that any sentence in the monadic second-order logic of matroids can be tested in polynomial time, when the input is limited to a class of $${\mathbb {F}}$$ F -representable matroids with bounded branch-width (where $${\mathbb {F}}$$ F is a finite field). If each matroid in a class can be decomposed by a subcubic tree in such a way that only a bounded amount of information flows across displayed separations, then the class has bounded decomposition-width. We introduce the pigeonhole property for classes of matroids: if every subclass with bounded branch-width also has bounded decomposition-width, then the class is pigeonhole. An efficiently pigeonhole class has a stronger property, involving an efficiently-computable equivalence relation on subsets of the ground set. We show that Hliněný’s Theorem extends to any efficiently pigeonhole class. In a sequel paper, we use these ideas to extend Hliněný’s Theorem to the classes of fundamental transversal matroids, lattice path matroids, bicircular matroids, and $$H$$ H -gain-graphic matroids, where H is any finite group. We also give a characterisation of the families of hypergraphs that can be described via tree automata: a family is defined by a tree automaton if and only if it has bounded decomposition-width. Furthermore, we show that if a class of matroids has the pigeonhole property, and can be defined in monadic second-order logic, then any subclass with bounded branch-width has a decidable monadic second-order theory.

When acquiring information systems, public entities face a dilemma. On the one hand, they want to procure the system that best suits their needs, which often requires lengthy dialogues with vendors. At the same time, they are restricted by government regulations that mandate limited dialogue in the interests of transparency and equal opportunities for all vendors. To examine how public entities deal with this, we followed three procurement projects in Norway. We show that this dilemma manifests itself as a dialectic between the thesis of getting the system requirements right and the antithesis of strictly adhering to regulations. Public entities search for a resolution of this dialectic through two syntheses: selecting an appropriate tendering procedure, and learning how to specify requirements through networks of peer public entities. Our findings reveal that the syntheses are possible because the dialectic is actually complimentary, both the thesis and the antithesis are needed to create the joint outcome that satisfies both. The resolution of the dialectic unfolds differently over time. Our study contributes to the relatively neglected stream of IS research on dialectics that explicitly searches for a synthesis while revealing the complementarity of the dialectic. We show how time plays a nuanced role in the resolution of the dialectic situation.

We outline a Punctuated Socio-Technical Information System Change model. The model recognizes both incremental and punctuated socio-technical change in the context of information systems at multiple levels – the work system level, the building system level, and the organizational environment. It uses socio-technical event sequences and their properties to explain how a change outcome emerged. The critical events in these sequences correspond to gaps in socio-technical systems. By conceiving information system (IS) change as a multi-level and punctuated sequence of socio-technical events, IS researchers can conceive plausible and accurate process explanations of IS change outcomes, including IS failures. Such explanations are located in the middle range and thus avoid the highly abstract and stylized closed-boxed factor models of change, but go beyond the idiographic open box histories of singular change processes.

In the last 10 years, the majority of large companies have attempted to install Enterprise Resource Planning (ERP) systems, replacing functional systems with a standardised company-wide system. However, making an ERP system work, we contend, is more than an issue of technical expertise or social accommodation: it is an ongoing, dynamic interaction between the ERP system, different groups in an organisation and external groups, such as vendors, management consultants and shareholders. This paper builds this argument using the example of management accountants in the U.K. based on evidence from a survey and several case studies. Drawing on work by Scarbrough and Corbett, we apply and develop a model, the technology power loop, linking technology, the control of technology and expertise to explain issues of how ERP systems are made to work and how expert groups seek to influence this development. We show, using empirical evidence from a survey and several case studies, that the relationship of accountants and technologies such as ERPs has become increasingly intertwined, but accountants continue to use their position to reshape their professional expertise wherever possible. However, our evidence also shows that neglect in this area allows other groups to wrest control from management accountants and make ERPs work for themselves.