Fostering Program Comprehension in Novice Programmers - Learning Activities and Learning Trajectories

This working group asserts that Program Comprehension (ProgComp) plays a critical part in the process of writing programs. For example, this paper is written from a basic draft that was edited and revised until it clearly presented our idea. Similarly, a program is written incrementally, with each step tested, debugged and extended until the program achieves its goal. Novice programmers should develop program comprehension skills as they learn to code so that they are able both to read and reason about code created by others, and to reflect on their code when writing, debugging or extending it. To foster such competencies our group identified two main goals: (g1) to collect and define learning activities that explicitly address key components of program comprehension and (g2) to define tentative theoretical learning trajectories that will guide teachers as they select and sequence those learning activities in their CS0/CS1/CS2 or K-12 courses. The WG has completed the first goal and laid down a strong foundation towards the second goal as presented in this report. After a thorough literature review, a detailed description of the Block Model is provided, as this model has been used with a dual purpose, to classify and present an extensive list of ProgComp tasks, and to describe a possible learning trajectory for a complex task, covering different cells of the Block Model matrix. The latter is intended to help instructors to decompose complex tasks and identify which aspects of ProgComp are being fostered

Tissue specific mutagenic and carcinogenic responses in NER defective mouse models.

Several mouse models with defects in genes encoding components of the nucleotide excision repair (NER) pathway have been developed. In NER two different sub-pathways are known, i.e. transcription-coupled repair (TC-NER) and global-genome repair (GG-NER). A defect in one particular NER protein can lead to a (partial) defect in GG-NER, TC-NER or both. GG-NER defects in mice predispose to cancer, both spontaneous as well as UV-induced. As such these models (Xpa, Xpc and Xpe) recapitulate the human xeroderma pigmentosum (XP) syndrome. Defects in TC-NER in humans are associated with Cockayne syndrome (CS), a disease not linked to tumor development. Mice with TC-NER defects (Csa and Csb) are - except for the skin - not susceptible to develop (carcinogen-induced) tumors. Some NER factors, i.e. XPB, XPD, XPF, XPG and ERCC1 have functions outside NER, like transcription initiation and inter-strand crosslink repair. Deficiencies in these processes in mice lead to very severe phenotypes, like trichothiodystrophy (TTD) or a combination of XP and CS. In most cases these animals have a (very) short life span, display segmental progeria, but do not develop tumors. Here we will overview the available NER-related mouse models and will discuss their phenotypes in terms of (chemical-induced) tissue-specific tumor development, mutagenesis and premature aging features

Production systems as control structures for programming languages

Production systems have recently found considerable favor as the control structure for systems in artificial intelligence. This work has lead other researchers to suggest the creation of languages which have production systems as a primary or alternative control structure. This paper explores some of the possibilities available in these languages; an experimental language with a production system control structure is presented, along with an example program written in it. Appropriate application domains for languages of this type are discussed, and the potential for using them with future hardware architectures is explored

Production systems as control structures for programming languages

Production systems have recently found considerable favor as the control structure for systems in artificial intelligence. This work has lead other researchers to suggest the creation of languages which have production systems as a primary or alternative control structure. This paper explores some of the possibilities available in these languages; an experimental language with a production system control structure is presented, along with an example program written in it. Appropriate application domains for languages of this type are discussed, and the potential for using them with future hardware architectures is explored

Towards a theory of the cognitive processes in computer programming

While only in the past ten years have large numbers of people been engaged in computer programming, a small body of studies on this activity have already been accumulated. These studies are, however, largely atheoretical. The work described here has as its goal the creation of an information processing theory sufficient to describe the findings of these studies. The theory postulates understanding, method-finding, and coding processes in writing programs, and presents an explicit model for the coding process

How a programmer understands a program : a model

In a large variety of programming situations, a programmer is required to understand a program that someone else has written. A model has been created for the behavior seen in the verbal protocol of a programmer on a sample understanding task. The model is based on a theory of understanding which stresses the role of the programmer's apriori hypotheses or guesses about the program structure. Organization of the model is that of a production system, a structure which appears particularly well-suited to the asynchronous, non-sequential nature of the input

How a programmer understands a program : a model

In a large variety of programming situations, a programmer is required to understand a program that someone else has written. A model has been created for the behavior seen in the verbal protocol of a programmer on a sample understanding task. The model is based on a theory of understanding which stresses the role of the programmer's apriori hypotheses or guesses about the program structure. Organization of the model is that of a production system, a structure which appears particularly well-suited to the asynchronous, non-sequential nature of the input