Problem Trends -e Why Hard? What about software Syllabus Too complex for complete analysis Separation into non-interacting subsystems distorts the results The most important properties are emergent Too organized for statistics Too much underlying structure that distorts the statistics Organized Complexity"(Weinberg) Copyright Nancy Leveson, Sept 1999
Problem Trends Why Hard? What about software? Slyllabus Too complex for complete analysis: Separation into non-interacting subsystems distorts the results. The most important properties are emergent. Too organized for statistics Too much underlying structure that distorts the statistics. "Organized Complexity" (Weinberg) Copyright c Nancy Leveson, Sept. 1999 �
Problem Trends Why Hard? Syllabus Large discrete state spaces Continuous vs discrete math acks repetitive structure found in computer circuitry Cannot test exhaustively Intangibility Invisible interfaces Hard to experiment with and manage Transient hardware faults vs. software errors Hard to diagnose problems Copyright ncy Leveson, Sept 1999
�� �� ������������������������ Problem Trends Why Hard? Slyllabus � Other Factors � � � � � � � � � � � � � � � � � � � � � � � �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� Large discrete state spaces Continuous vs. discrete math Lacks repetitive structure found in computer circuitry Cannot test exhaustively Intangibility � � Invisible interfaces Hard to experiment with and manage Transient hardware faults vs. software errors � � Hard to diagnose problems Copyright c Nancy Leveson, Sept. 1999 �
Problem Trends Why Hard? Syllabus And one more No historical usage information to allow measurement, evaluation and improvement of standard designs over time Always specially constructed Usually doing new things Copyright Nancy Leveson, Sept 1999
��������������������������� Problem Trends Why Hard? Slyllabus And One More � � � � � � � � � � � � � � � � � � � � � � � � � � � No historical usage information to allow measurement, evaluation, and improvement of standard designs over time. Always specially constructed. Usually doing new things. c Copyright Nancy Leveson, Sept. 1999 �
Problem Trends Why hard? Syllabus 1. Students will be able to evaluate software engineering techniques and approaches barefoot irreverance to their studies. They are here 2 It is important that students bring a certain ragamuffin not to worship what is known, but to question it. lacob Bronowski. The ascent of Man The developed theories .. have rarely been subjected to empirical testing and so their value remains unknown. They provide zealots with opportunities to market a rash of seminars the new technologies. When the theories are subjectto ing and courses and to flood the literature with papers advocating testing, what little evidence has been obtained sometimes suggests that the claimed benefits, in fact, may not exist. Vessey and weber Copyright ncy Leveson, Sept. 1999
������������������������������ ������������������������������ Problem Trends Why Hard? Slyllabus � Class Objectives � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 1. Students will be able to evaluate software engineering techniques and approaches. "It is important that students bring a certain ragamuffin barefoot irreverance to their studies. They are here not to worship what is known, but to question it." Jacob Bronowski, The Ascent of Man "The developed theories ...have rarely been subjected to empirical testing, and so their value remains unknown. They provide zealots with opportunities to market a rash of seminars and courses and to flood the literature with papers advocating the new technologies. When the theories are subjected to testing, what little evidence has been obtained sometimes suggests that the claimed benefits, in fact, may not exist. Vessey and Weber c Copyright Nancy Leveson, Sept. 1999 �
Proble Trends Why Ha Syllabus Class Objectives 2. Students will be able to exercise professional judgment in selecting an approach for a particular project based on an understanding of How the present state of software practice came about What was tried in the past What worked and what did not work Copyright Nancy Leveson, Sept 1999
������������������������������ Problem Trends Why Hard? Syllabus Class Objectives � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 2. Students will be able to exercise professional judgment in selecting an approach for a particular project based on an understanding of: How the present state of software practice came about What was tried in the past What worked and what did not work Why c Copyright Nancy Leveson, Sept. 1999 �