We biomechanically investigated whether the standard dynamic hip screw (DHS) or the DHS blade achieves better fixation in bone with regard to resistance to pushout, pullout and torsional stability. The experiments were undertaken in an artificial bone substrate in the form of polyurethane foam blocks with predefined mechanical properties. Pushout tests were also repeated in cadaveric femoral he...

Sesqui-pushout (sqpo) rewriting—“sesqui” means “one and a half” in Latin—is a new algebraic approach to abstract rewriting in any category. sqpo rewriting is a deterministic and conservative extension of double-pushout (dpo) rewriting, which allows to model “deletion in unknown context”, a typical feature of single-pushout (spo) rewriting, as well as cloning. After illustrating the expressivene...

We characterize the pairs of partial homomorphisms of total Σ-algebras that have a pushout in the corresponding category, for an arbitrary signature Σ. This characterization provides the application condition for the single-pushout approach to the transformation of total algebras.

It belongs to the folklore that graph grammars can be seen as a proper generalisation of Petri nets. In this paper we show how this intuitive relationship can be made formal. The double-pushout approach to graph rewriting turns out to be strictly related to Petri nets with read and inhibitor arcs, while the single-pushout approach has strong connections to Petri nets with read and reset arcs.

Single pushout graph transformations at injective matches are extended by negative application conditions. It is shown, how right-sided application conditions can be transformed into equivalent left-sided ones. Based on this result, conditional derived rules are introduced and a theorem, similiar to the double pushout embedding theorem is shown. Finally, three variants of contextual application...

Algebraic graph rewriting, which works by first removing the part of the graph to be regarded as garbage, and then gluing in the new part of the graph, is contrasted with term graph rewriting, which works by first gluing in the new part of the graph (the contractum) and performing redirections, and then removing garbage. It is shown that in the algebraic framework these two strategies can be re...

We continue here the development of our description of the pullback approach to graph rewriting-already shown to encompass both the NCE and the double-pushout approach, by describing parallel application of rewriting rules. We show that this new framework provides a genuine deenition of parallel rewriting (parallel application of several rewriting rules at several diierent places in the graph i...

The paper proposes a variant of sesqui-pushout rewriting (SqPO) that allows one to develop the theory of nested application conditions (NACs) for arbitrary rule spans; this is a considerable generalisation compared with existing results for NACs, which only hold for linear rules (w.r.t. a suitable class of monos). Besides this main contribution, namely an adapted shifting construction for NACs,...