1. A computer implemented method for approving a group purchase request for a group of articles, wherein the group comprises at least one article, the method comprising: selecting, by one or more processors, a sub-group of articles, wherein a unique article approval index is assigned to each of the articles of the group of articles and a highest article approval index is determined among the unique article approval indexes of the articles of the group, wherein an article of the group is selected into the sub-group based on the article of the group complying with at least one of the following article selection criteria: the unique article approval index of the article of the group is above a predetermined approval index threshold, the unique article approval index of the article of the group is equal to the highest article approval index; generating, by the one or more processors, a dedicated approval sequence for each article, wherein approving the article purchase request for each article requires approval at all approval steps of the approval sequence, wherein the generating an approval sequence for an article comprises: constructing, by the one or more processors, an approval sequence of the article based on approval steps of approval sequences of one or more similar articles, wherein a number of the one or more similar articles comprise a threshold number above a predetermined similarity threshold and the one or more similar articles each have a unique pair similarity index above a predetermined article similarity threshold the constructing comprising: registering, by the one or more processors, in a database communicatively coupled to the one or more processors, attribute values characterizing attributes of the article, wherein each attribute is characterized by a corresponding attribute value; determining, by the one or more processors, a level of similarity between values of registered attributes of the article and values of registered attributes of one or more articles registered in the database; based on the level of similarity, calculating, by the one or more processors, a unique pair similarity index for the article and each of the one or more articles, wherein the unique pair similarity index represents a level of similarity between the article and each of the one or more articles; determining, by the one or more processors, which of the one or more articles comprise one or more similar articles by determining for which of the one or more articles the unique pair similarity index of the article and an article of the one or more articles is above a predetermined article similarity threshold; determining, by the one or more processors, that the number of articles in the one or more similar articles is above the a threshold number; and constructing, by the one or more processors, the approval sequence of the article out of the approval steps of the approval sequences of the one or more similar articles; and receiving, by the one or more processors, a group purchase request for the group of articles comprising an article purchase request of each of the articles of the group; and automatically approving, by the one or more processors, the group purchase request for the group based on approval of a group purchase request for the sub-group, based on automatically applying the dedicated approval sequence for each article.