*Raya Fidel*

- Published in print:
- 2012
- Published Online:
- August 2013
- ISBN:
- 9780262017008
- eISBN:
- 9780262301473
- Item type:
- book

- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262017008.001.0001
- Subject:
- Information Science, Information Science

Human information interaction (HII) is an emerging area of study that investigates how people interact with information; its subfield human information behavior (HIB) is a flourishing, active ...
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Human information interaction (HII) is an emerging area of study that investigates how people interact with information; its subfield human information behavior (HIB) is a flourishing, active discipline. Yet despite their obvious relevance to the design of information systems, these research areas have had almost no impact on systems design. One issue may be the contextual complexity of human interaction with information; another may be the difficulty in translating real-life and unstructured HII complexity into formal, linear structures necessary for systems design. This book proposes a research approach that bridges the study of human information interaction and the design of information systems: cognitive work analysis (CWA). Developed by Jens Rasmussen and his colleagues, CWA embraces complexity and provides a conceptual framework and analytical tools that can harness it to create design requirements. It offers an ecological approach to design, analyzing the forces in the environment that shape human interaction with information. The book reviews research in HIB, focusing on its contribution to systems design, and then presents the CWA framework. It shows that CWA, with its ecological approach, can be used to overcome design challenges and lead to the development of effective systems. Researchers and designers who use CWA can increase the diversity of their analytical tools, providing them with an alternative approach when they plan research and design projects. The CWA framework enables a collaboration between design and HII that can create information systems tailored to fit human lives.Less

Human information interaction (HII) is an emerging area of study that investigates how people interact with information; its subfield human information behavior (HIB) is a flourishing, active discipline. Yet despite their obvious relevance to the design of information systems, these research areas have had almost no impact on systems design. One issue may be the contextual complexity of human interaction with information; another may be the difficulty in translating real-life and unstructured HII complexity into formal, linear structures necessary for systems design. This book proposes a research approach that bridges the study of human information interaction and the design of information systems: cognitive work analysis (CWA). Developed by Jens Rasmussen and his colleagues, CWA embraces complexity and provides a conceptual framework and analytical tools that can harness it to create design requirements. It offers an ecological approach to design, analyzing the forces in the environment that shape human interaction with information. The book reviews research in HIB, focusing on its contribution to systems design, and then presents the CWA framework. It shows that CWA, with its ecological approach, can be used to overcome design challenges and lead to the development of effective systems. Researchers and designers who use CWA can increase the diversity of their analytical tools, providing them with an alternative approach when they plan research and design projects. The CWA framework enables a collaboration between design and HII that can create information systems tailored to fit human lives.

*Raymond M. Smullyan*

- Published in print:
- 1993
- Published Online:
- November 2020
- ISBN:
- 9780195082326
- eISBN:
- 9780197560426
- Item type:
- chapter

- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195082326.003.0009
- Subject:
- Computer Science, Mathematical Theory of Computation

§1. Complete Effective Inseparability. A disjoint pair (A1,A2) is by definition recursively inseparable if no recursive superset of A1 is disjoint from A2. This is ...
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§1. Complete Effective Inseparability. A disjoint pair (A1,A2) is by definition recursively inseparable if no recursive superset of A1 is disjoint from A2. This is equivalent to saying that for any disjoint r.e. supersets ωi and ωj of A1 and A2, the set ωi is not the complement of ωj —in other words, there is a number n outside both ωi and ωj. The disjoint pair (A1,A2) is called effectively inseparable—abbreviated E.I.—if there is a recursive function δ(x, y)—called an E.I. function for (A1, A2)—such that for any numbers i and j such that A1⊆ ωi and A2Í ωj. with ωi being disjoint from ωj, the number d(i , j) is outside both a;,- and ωj. We shall call a disjoint pair (A1, A2) completely E.I. if there is a recursive function δ(x, y)—which we call a complete E.I. function for (A1, A2)—such that for any numbers i and j, if A1⊆ ωi and A2Í ωj, then δ(i , j) Í ωi ↔ d(i , j)Í ωj (in other words, d(i, j) is either inside or outside both sets ωi and ωj.). [If ωi and ωj happen to be disjoint, then, of course, d(i, j) is outside both ωi and ωj, so any complete E.I. function for (A1,A2) is also an E.I. function for (A1,A2) In a later chapter, we will prove the non-trivial fact that if (A1, A2) is E.I. and A1 and A2 are both r.e., then (A1,A2) is completely E.I. [The proof of this uses the result known as the double recursion theorem, which we will study in Chapter 9.] Effective inseparability has been well studied in the literature. Complete effective inseparability will play a more prominent role in this volume—especially in the next few chapters. Proposition 1. (1) If (A1,A2) is completely E.I., then so is (A2,A1) —in fact, if d(x,y) is a complete E.I. function for (A1,A2), then d(y,x) is a complete E.I. function for (A2, A1).
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§1. Complete Effective Inseparability. A disjoint pair (A1,A2) is by definition recursively inseparable if no recursive superset of A1 is disjoint from A2. This is equivalent to saying that for any disjoint r.e. supersets ωi and ωj of A1 and A2, the set ωi is not the complement of ωj —in other words, there is a number n outside both ωi and ωj. The disjoint pair (A1,A2) is called effectively inseparable—abbreviated E.I.—if there is a recursive function δ(x, y)—called an E.I. function for (A1, A2)—such that for any numbers i and j such that A1⊆ ωi and A2Í ωj. with ωi being disjoint from ωj, the number d(i , j) is outside both a;,- and ωj. We shall call a disjoint pair (A1, A2) completely E.I. if there is a recursive function δ(x, y)—which we call a complete E.I. function for (A1, A2)—such that for any numbers i and j, if A1⊆ ωi and A2Í ωj, then δ(i , j) Í ωi ↔ d(i , j)Í ωj (in other words, d(i, j) is either inside or outside both sets ωi and ωj.). [If ωi and ωj happen to be disjoint, then, of course, d(i, j) is outside both ωi and ωj, so any complete E.I. function for (A1,A2) is also an E.I. function for (A1,A2) In a later chapter, we will prove the non-trivial fact that if (A1, A2) is E.I. and A1 and A2 are both r.e., then (A1,A2) is completely E.I. [The proof of this uses the result known as the double recursion theorem, which we will study in Chapter 9.] Effective inseparability has been well studied in the literature. Complete effective inseparability will play a more prominent role in this volume—especially in the next few chapters. Proposition 1. (1) If (A1,A2) is completely E.I., then so is (A2,A1) —in fact, if d(x,y) is a complete E.I. function for (A1,A2), then d(y,x) is a complete E.I. function for (A2, A1).