Predicate Logic for Software Engineering. David Lorge Parnas McMaster University, Ontario, Canada. Presentation for SwE Readings Class. By: Sridhar Pentapati. About Dave Parnas.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
By: Sridhar Pentapati
Progress in a scientific discipline can be measured by how quickly its founders are forgotten
Conventional interpretations of expressions that describe predicates are not suitable for use in software engineering because they do not deal with partial functions. Parnas’ team defines an interpretation for predicate expressions that is suitable for use in software documentation
Logic is in the eye of the logician. *Gloria Steinem
'Contrariwise', continued Tweedledee, 'if it was so, it might be, and if it were so, it would be; but as it isn't, it ain't. That's logic!' . *Lewis Carroll
Predicate Logic For Software Engineering
Logic is one thing, the human animal another. You can quite easily propose a logical solution to something and at the same time hope in your heart of hearts it won't work out. * Luigi Pirandello
Logic: The art of thinking and reasoning in strict accordance with the limitations and incapacities of the human misunderstanding. *Ambrose Bierce
The want of logic annoys. Too much logic bores. Life eludes logic, and everything that logic alone constructs remains artificial and forced. * André Gide
Predicate Logic For Software Engineering
The fact that logic cannot satisfy us awakens an almost insatiable hunger for the irrational. * A. N. Wilson
Predicate Logic For Software Engineering
From a drop of water a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other. * Sir Arthur Conan Doyle
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Logic is like the sword--those who appeal to it, shall perish by it. * Samuel Butler
Predicate Logic For Software Engineering
((x > 0) (y = x)) ((x 0) (y = -x)) (1)
to describe the behavior of a computer program
Predicate Logic For Software Engineering
The writer’s intent seems to be to write an expression that is equivalent to: y = |x| (2)the usual rules for evaluating such expressions require evaluation of all of the functions and relational operators before application of the logical operators to the truth-values that result. For every value of x other than 0, some component of expression (1) is undefined. With the standard interpretation of logical operators, which are defined only for two-value logics, the value of (1) is not defined except when x is assigned the value 0
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
A function that returns true or false. Conceptually it tests for a condition
The property that a bird is an eagle can be expressed by the predicate:
Predicate Logic For Software Engineering
Proposition 1 is true, whereas 2 is false
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Eg. <<true, false>, true, false>
You can only find truth with logic if you have already found truth without it
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
(x , P), (P), (P) (Q), (P) (Q), ¬(P)
There can never be surprises in logic
The mind has its own logic but does not often let others in on it. *Bernard Devoto
Mapping val for a term, t, and assignment, A:
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
Logic is a poor guide compared with custom. *Winston Churchill
Man has such a predilection for systems and abstract deductions that he is ready to distort the truth intentionally, he is ready to deny the evidence of his senses only to justify his logic. * Fyodor Mikhailovich Dostoyevsky
Logic, like whiskey, loses its beneficial effect when taken in very large quantities. * Lord Dunsany
Relational description of a program that searches B for the value of x
Predicate Logic For Software Engineering
(y = x) (y = -x)
Predicate Logic For Software Engineering
A mind all logic is like a knife all blade. It makes the hand bleed that uses it. *Rabindranath Tagore
Logic is the art of going wrong with confidence
Parnas believes that these are proper
decisions because:
Predicate Logic For Software Engineering
Predicate Logic For Software Engineering
- Kenneth Rosen, Fourth Edition
- Collected Papers by David L. Parnas
Predicate Logic For Software Engineering