## 2 Related Work
Additionally, these approaches are not based on BPMN notation, but on other languages and models (for example EPC). On the contrary, our proposal focuses, firstly, on providing a practical mechanism that, using a scalable repository of patterns, implements a solution in a fully automatic manner. Secondly, it is based on the BPMN language, the most widely used solution for the description of workflows in productive environments. In [15] it is used some of the reduction rules previously identified in [17], but with a different purpose. In this case, the objective is closer to BPMA. The authors of this work are concerned with the \"how\" component and focus their efforts on the elimination operation. They identify Single Entry Single Exit (SESE) blocks and substitute them with edges or paths. In this procedure, the authors apply reduction rules for simplifying some elements in the process model. Besides of these similarities, the simplification rules are not the most important part of that contribution. The core contribution of these works is concerned mainly with the aggregation and elimination operations on the so-called SESE blocks. Also, they are not focused on BPMN, as they are using what they call \"process schemes\", a process graph with atomic activities and control elements between them. Moreover, our approach is not limited only to Single Entry Single Exit blocks. Multiple Entry Multiple Exit blocks are also analysed. It is common in organisations to work with families of process variants. In this way, the conventional modelling languages have not specific support to represent these families. Over the past decade, several approaches have studied the Business Process Variability Modeling (BPVM) field in order to tackle this issue by extending the conventional business process modellinglanguages [18]. Presents a complete survey in the BPVM domain. It analyses 66 relevant publication from the year 2000 that cover 23 approaches to solving the problem. According to the variability mechanism, the approaches can be sorted into four classes: node configuration, element annotation, activity specialisation and fragment customisation. The approach proposed in the current paper can be categorised in the fourth class: fragment customisation. This class includes the works that propose the manipulation (insert, delete or modify) of entire fragments in order to create variation and customisation of the base process model. This class includes two main groups of approaches: Process variants by options (the most relevant works are [19; 20; 21; 22]) and Template and Rules (the most relevant works are [23; 24]). In the first group, the main idea is to mark the process model with the called adjustment points and to perform the change operations over these predefined points. This approach supports four types of operations to change the process flow: delete, insert, modify and move. For example, with the move operation, it is possible to relocate a fragment in the base model bounded by two adjustment points to another part bounded by two distinct adjustment points. The second group associates a set of business rules to a specific template model that will be used to perform the change operations. The different process model perspectives allowed in the family can be inferred by using the rules associated with the template model. Meanwhile the main concepts behind all the BPVM approaches are very similar to our work, the philosophy and the application of the proposal are quite different. In particular, our approach uses a combination of the insert and delete basic manipulations to implement a complex operation: replace. In our case, a full Multiple Entry Multiple Exit fragment will be replaced by a simplified version offering the same behaviour but using fewer elements. One of the keys of our proposal lies in to obtain an efficient process model (i.e., with fewer elements). Moreover, our approach is generic and can be applied without modification to any BPMN process model.