The KeY tool is used in formal verification of Java programs. It accepts specifications written in the Java Modeling Language to Java source files. These are transformed into theorems of dynamic logic and then compared against program semantics that are likewise defined in terms of dynamic logic. KeY is significantly powerful in that it supports both interactive (i.e. by hand) and fully automated correctness proofs. Failed proof attempts can be used for a more efficient debugging or verification-based testing. There have been several extensions to KeY in order to apply it to the verification of C programs or hybrid systems. KeY is jointly developed by Karlsruhe Institute of Technology, Germany; Technische Universität Darmstadt, Germany; and Chalmers University of Technology in Gothenburg, Sweden and is licensed under the GPL. Overview The usual user input to KeY consists of a Java source file with annotations in JML. Both are translated to KeY's internal representation, dynamic logic. From the given specifications, several proof obligations arise which are to be discharged, i.e. a proof has to be found. To this ends, the program is symbolically executed with the resulting changes to program variables stored in so-called updates. Once the program has been processed completely, there remains a first-order logic proof obligation. At the heart of the KeY system lies a first-order theorem prover based on sequent calculus, which is used to close the proof. Interference rules are captured in so called taclets which consist of an own simple language to describe changes to a sequent. Java Card DL The theoretical foundation of KeY is a formal logic called Java Card DL. DL stands for Dynamic Logic. It is a version of a first-order dynamic logic tailored to Java Card programs. As such, it for example allows statements (formulas) like , which intuitively says that the post-condition must hold in all program states reachable by executing the Java Card program in any state that satisfies the pre-condition . This is equivalent to in Hoare calculus if and are purely first order. Dynamic logic, however, extends Hoare logic in that formulas may contain nested program modalities such as , or that quantification over formulas which contain modalities is possible. There is also a dual modality which includes termination.

From Wikipedia (CC BY-SA 4.0).

Notable quotes

“I don't know the key to success, but the key to failure is trying to please everybody.”
— Anonymous; this is often misattributed to Bill Cosby, who actually cites this as a sound advice he once read elsewhere, in "Dr. Bill Cosby" in Ebony, Vol. 32, No. 8 (June 1977), p. 136
“The key is to keep company only with people who uplift you, whose presence calls forth your best.”
— Epictetus, as quoted in The Art of Living : The Classic Manual on Virtue, Happiness, and Effectiveness, A New Interpretation by Sharon Lebell (1994)
“Prophets hold a key to the lock in a language. The mechanical image remains only an image to them. This is not a mechanical universe.”
— Frank Herbert in God Emperor of Dune (1981)
“In oneself lies the whole world and if you know how to look and learn, the door is there and the key is in your hand. Nobody on earth can give you either the key or the door to open, except yourself.”
— Jiddu Krishnamurti, as quoted in Perfecting Ourselves : Coordinating Body, Mind, and Spirit (2002) by Aaron Hoopes, p. 64
“You unlock this door with the key of imagination. Beyond it is another dimension—a dimension of sound, a dimension of sight, a dimension of mind. You're moving into a land of both shadow and substance, of things and ideas. You've just crossed over into the Twilight Zone.”
— Rod Serling Twilight Zone opening seasons 4&5
“We receive His peace when we ask Him for it. We keep His peace by extending it to others. Those are the keys and there are no others. Spiritual wisdom is now available to everyone, disseminated to the masses as never before in world history.”
— Marianne Williamson, in Illuminata : Thoughts, Prayers, Rites of Passage (1994), Part I : Thoughts, Ch. 2 : The Luminous Mind, p. 29

Quotes via Wikiquote (CC BY-SA), each with its original source.

Overview

The KeY tool is used in formal verification of Java programs. It accepts specifications written in the Java Modeling Language to Java source files. These are transformed into theorems of dynamic logic and then compared against program semantics that are likewise defined in terms of dynamic logic. KeY is significantly powerful in that it supports both interactive (i.e. by hand) and fully automated correctness proofs. Failed proof attempts can be used for a more efficient debugging or verification-based testing. There have been several extensions to KeY in order to apply it to the verification of C programs or hybrid systems. KeY is jointly developed by Karlsruhe Institute of Technology, Germany; Technische Universität Darmstadt, Germany; and Chalmers University of Technology in Gothenburg, Sweden and is licensed under the GPL. Overview The usual user input to KeY consists of a Java source file with annotations in JML. Both are translated to KeY's internal representation, dynamic logic. From the given specifications, several proof obligations arise which are to be discharged, i.e. a proof has to be found. To this ends, the program is symbolically executed with the resulting changes to program variables stored in so-called updates. Once the program has been processed completely, there remains a first-order logic proof obligation. At the heart of the KeY system lies a first-order theorem prover based on sequent calculus, which is used to close the proof. Interference rules are captured in so called taclets which consist of an own simple language to describe changes to a sequent. Java Card DL The theoretical foundation of KeY is a formal logic called Java Card DL. DL stands for Dynamic Logic. It is a version of a first-order dynamic logic tailored to Java Card programs. As such, it for example allows statements (formulas) like , which intuitively says that the post-condition must hold in all program states reachable by executing the Java Card program in any state that satisfies the pre-condition . This is equivalent to in Hoare calculus if and are purely first order. Dynamic logic, however, extends Hoare logic in that formulas may contain nested program modalities such as , or that quantification over formulas which contain modalities is possible. There is also a dual modality which includes termination.

From Wikipedia (CC BY-SA 4.0).

The KeY tool is used in formal verification of Java programs. It accepts specifications written in the Java Modeling Language to Java source files. These are transformed into theorems of dynamic logic and then compared against program semantics that are likewise defined in terms of dynamic logic. KeY is significantly powerful in that it supports both interactive (i.e. by hand) and fully automated correctness proofs. Failed proof attempts can be used for a more efficient debugging or verification-based testing. There have been several extensions to KeY in order to apply it to the verification of C programs or hybrid systems. KeY is jointly developed by Karlsruhe Institute of Technology, Germany; Technische Universität Darmstadt, Germany; and Chalmers University of Technology in Gothenburg, Sweden and is licensed under the GPL.

Notable quotes

“I don't know the key to success, but the key to failure is trying to please everybody.”
— Anonymous; this is often misattributed to Bill Cosby, who actually cites this as a sound advice he once read elsewhere, in "Dr. Bill Cosby" in Ebony, Vol. 32, No. 8 (June 1977), p. 136
“The key is to keep company only with people who uplift you, whose presence calls forth your best.”
— Epictetus, as quoted in The Art of Living : The Classic Manual on Virtue, Happiness, and Effectiveness, A New Interpretation by Sharon Lebell (1994)
“Prophets hold a key to the lock in a language. The mechanical image remains only an image to them. This is not a mechanical universe.”
— Frank Herbert in God Emperor of Dune (1981)
“In oneself lies the whole world and if you know how to look and learn, the door is there and the key is in your hand. Nobody on earth can give you either the key or the door to open, except yourself.”
— Jiddu Krishnamurti, as quoted in Perfecting Ourselves : Coordinating Body, Mind, and Spirit (2002) by Aaron Hoopes, p. 64
“You unlock this door with the key of imagination. Beyond it is another dimension—a dimension of sound, a dimension of sight, a dimension of mind. You're moving into a land of both shadow and substance, of things and ideas. You've just crossed over into the Twilight Zone.”
— Rod Serling Twilight Zone opening seasons 4&5
“We receive His peace when we ask Him for it. We keep His peace by extending it to others. Those are the keys and there are no others. Spiritual wisdom is now available to everyone, disseminated to the masses as never before in world history.”
— Marianne Williamson, in Illuminata : Thoughts, Prayers, Rites of Passage (1994), Part I : Thoughts, Ch. 2 : The Luminous Mind, p. 29