During software requirements analysis, developers and stakeholders have many alternatives of requirements to be achieved and should make decisions to select an alternative out of them. There are two significant points to be considered for supporting these decision making processes in requirements analysis; 1) dependencies among alternatives and 2) evaluation based on multi-criteria and their trade-off. This paper proposes the technique to address the above two issues by using an extended version of goal-oriented analysis. In goal-oriented analysis, elicited goals and their dependencies are represented with an AND-OR acyclic directed graph. We use this technique to model the dependencies of the alternatives. Furthermore we associate attribute values and their propagation rules with nodes and edges in a goal graph in order to evaluate the alternatives with them. The attributes and their calculation rules greatly depend on the characteristics of a development project. Thus, in our approach, we select and use the attributes and their rules that can be appropriate for the project. TOPSIS method is adopted to show alternatives and their resulting attribute values.

Ordered attribute grammars (OAGs for short) are a useful class of attribute grammars (AGs). For some attribute grammars, even though they are not circular, OAG circularity test reports that they are not ordered and fails to generate attribute evaluators because some approximation introduces circularities (called type 3 circularities in this paper). First we discuss that it is sometimes difficult for programmers to eliminate type 3 circularities by hand. Second, to reduce this difficulty, we propose a new AG class called OAG* that produces less type 3 circularities than OAG while preserving the positive characteristic of OAG. OAG* uses a global dependency graph GDS that provides a new approximation algorithm. We obtained good results with our experimental implementation of OAG*. It is shown that OAG* is different from the existing GAG and Eli/Liga systems. Finally, two combinations of Eli/Liga and OAG* are provided.

Deforestation is a well-known program transformation technique which eliminates intermediate data structures that are passed between functions. One of its weaknesses is the inability to deforest programs using accumulating parameters. We show how certain kinds of intermediate lists produced by accumulating parameters can be deforested. In this paper we introduce an accumulative variant of foldr, called rdlof, and show the composition of functions defined by foldr and rdlof. As a simplified instance of foldr and rdlof, we then examine dmap, an accumulative extension of map, and give the corresponding fusion rules. While the associated composition rules cannot capture all deforestation problems, they can handle accumulator fusion of fold- and map-style functions in a simple manner. The rules for accumulator fusion presented here can also be viewed as a restricted composition scheme for attribute grammars, which in turn may help us to bridge the gap between the attribute and functional worlds.

We present two efficient attribute evaluator construction methods for a wide subclass of L-attributed grammars by enumeration of attributed items during one-pass bottom-up parsing. We have already proposed a construction method of a parser/evaluator for the subclass of L-attributed grammar. However the evaluator produced by our previous method uses a great number of attributed items to evaluate all attributes of a given input string. In this paper we propose two generalized methods to reduce the number of attributed itmes used in attribute evaluation. Our methods allow us to evaluate all attributes taking advantage of the use of available lookahead information.

When a group of developers are involved in the distributed development of some software product, they must communicate with one another frequently to exchange information about the product. To reduce the penalty of communication, the support environment should provide developers with their necessary information and update the information automatically while the product is modified by developers. Furthermore, the environment must meet the following requirements despite of workstation failures: whether a specific information is correct or not should always be decidable; as much information as possible should be updated correctly and efficiently. This paper presents a framework to construct such a fault-tolerant environment based on attribute grammars. In the framework, a product is represented by an attributed tree, which is partitioned into several subtrees {T1,,Tm}. Attribute values in each subtree Ti(1im) express the information about the product required by a developer. We introduce a set of redundant data and algorithms to meet the fault-tolerance requirements mentioned above. The correctness of an attribute value in Ti can then be decided in O(mn0log n) time, where n0n, and n is the number of attribute instances in Ti. All available attribute values can be updated with time complexity O(m2n1 log n) and communication complexity O(m2), where n1 is the number of attribute instances that must be reevaluated.