You are provided with the abstract of a scientific paper and the abstracts of the papers it references. Your task is to write a Related Work section for the main paper. This section should concisely summarize and integrate the key points from the cited abstracts, reflecting how they relate to the main paper's contributions and context. In your summary, use numerical citation markers like [1], [2], etc., to refer to the corresponding papers.

Main Abstract:
One of the key concepts in testing is that of adequate test sets. A test selection criterion decides which test sets are adequate. In this paper, a language schema for specifying a large class of test selection criteria is developed; the schema is based on two operations for building complex criteria from simple ones. Basic algebraic properties of the two operations are derived. In the second part of the paper, a simple language-an instance of the general schema-is studied in detail, with the goal of generating small adequate test sets automatically. It is shown that one version of the problem is intractable, while another is solvable by an efficient algorithm. An implementation of the algorithm is described.

Cited Abstract(s):
[1]: An approach to functional testing is described in which the design of a program is viewed as an integrated collection of functions. The selection of test data depends on the functions used in the design and on the value spaces over which the functions are defined. The basic ideas in the method were developed during the study of a collection of scientific programs containing errors. The method was the most reliable testing technique for discovering the errors. It was found to be significantly more reliable than structural testing. The two techniques are compared and their relative advantages and limitations are discussed.
In his discussion of functional testing, Howden [1] stresses the need to identify input domains, and gives guidelines for systematic selection of test points for several types of input values that occur in scientific programs. Our basic philosophy is similar to Howden's; we develop this point of view further, by automating part of the selection process.