An abstract formulation of data processing problems

Abstract

SUMMARY A data processing problem can be described in terms of four kinds of components: 1) Information set, P;, This is a llst' of al) is~ossibte ;nformation ;terns belonging to the same class; from the items in these lists are drawn the data which flow through the system. Examples of ;terns which make up information sets are customers' names and addresses, part numbers, unit prices, salesmen names, etc. Documenfs~ D]o Documents are a collection of related information items Dik0 They are generally inputs or outputs, e.g., shipping notice, invoicer et"co Each document consists of K entries, e.g., date, customer's name and addressr etc. 3) Relationships among the Dj, Djk, andPi. These will be discussed below. An abstract statement of a problem is obtained by the preparation of two lists. The first is a llst of the information sets (Pi) along with certain data about the number of items in each set, the number of characters required for each item, and the relationships among sets. The second llst presents for each document (Dj) tile items (Djk) on the document and the information set each item belongs to. It also presents the relationships associated wlth all the items in the system and the operational requirements of the system. A simplified version of a billing operation consisting of a shipping notice, invoice, payment1 monthly statement and daily sales report has been stated in abstract terms. One of the relationshlps that exists between information sets is a one-.to-one