2024-04-29 13:29:03 +00:00
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---
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title: Assertions
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TARGET DECK: Obsidian::STEM
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FILE TAGS: programming::assertions
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tags:
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- assertions
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- programming
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---
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## Overview
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2024-04-29 20:47:33 +00:00
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Define $\{Q\}\; S\; \{R\}$ as the predicate:
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> If execution of $S$ is begun in a state satisfying $Q$, then it is guaranteed to terminate in a finite amount of time in a state satisfying $R$.
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%%ANKI
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Basic
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*What* is $Q$ in predicate $\{Q\}\; S\; \{R\}$?
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Back: A predicate.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640219-->
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END%%
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%%ANKI
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Basic
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What name is given to $Q$ in $\{Q\}\; S\; \{R\}$?
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Back: The precondition of $S$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640222-->
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END%%
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%%ANKI
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Basic
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*What* is $R$ in predicate $\{Q\}\; S\; \{R\}$?
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Back: A predicate.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640224-->
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END%%
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%%ANKI
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Basic
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What name is given to $R$ in $\{Q\}\; S\; \{R\}$?
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Back: The postcondition of $S$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640226-->
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END%%
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%%ANKI
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Basic
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*What* is $S$ in predicate $\{Q\}\; S\; \{R\}$?
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Back: A program (a sequence of statements).
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640227-->
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END%%
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%%ANKI
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Basic
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What is the antecedent of $\{Q\}\; S\; \{R\}$ in English?
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Back: $S$ is executed in a state satisfying $Q$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640229-->
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END%%
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%%ANKI
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Basic
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2024-05-09 20:29:12 +00:00
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What is the consequent of $\{Q\}\; S\; \{R\}$ in English?
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2024-04-29 20:47:33 +00:00
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Back: $S$ terminates in a finite amount of time in a state satisfying $R$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640231-->
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END%%
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%%ANKI
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Basic
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How is $\{Q\}\; S\; \{R\}$ defined?
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Back: If $S$ is executed in a state satisfying $Q$, it terminates in a finite amount of time in a state satisfying $R$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640232-->
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END%%
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%%ANKI
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Basic
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How is $\{x = X \land y = Y\}\; swap\; \{x = Y \land y = X\}$ rewritten without free identifiers?
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Back: $\forall x, y, X, Y, \{x = X \land y = Y\}\; swap\; \{x = Y \land y = X\}$
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640234-->
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END%%
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%%ANKI
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Basic
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What name is given to $X$ in e.g. $\{x = X\}\; S\; \{y = Y\}$?
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Back: The initial value of $x$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640235-->
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END%%
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%%ANKI
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Basic
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How is $\{Q\}\; S\; \{R\}$ augmented so that $x$ has initial value $X$?
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Back: $\{Q \land x = X\}\; S\; \{R\}$
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640237-->
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END%%
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%%ANKI
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Basic
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What name is given to $Y$ in e.g. $\{x = X\}\; S\; \{y = Y\}$?
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Back: The final value of $y$.
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640238-->
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END%%
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%%ANKI
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Basic
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How is $\{Q\}\; S\; \{R\}$ augmented so that $y$ has final value $X$?
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Back: $\{Q\}\; S\; \{R \land y = X\}$
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640240-->
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END%%
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%%ANKI
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Basic
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How is $\{Q\}\; S\; \{R\}$ augmented so that $y$ has initial value $X$?
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Back: $\{Q \land y = X\}\; S\; \{R\}$
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Reference: Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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<!--ID: 1714420640241-->
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END%%
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2024-04-29 13:29:03 +00:00
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## Bibliography
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* Gries, David. *The Science of Programming*. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.
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