## Defaults in Specifications (1993)

Venue: | in [RE93 |

Citations: | 16 - 2 self |

### BibTeX

@INPROCEEDINGS{Ryan93defaultsin,

author = {Mark Ryan},

title = {Defaults in Specifications},

booktitle = {in [RE93},

year = {1993},

pages = {142--149}

}

### OpenURL

### Abstract

A formalism is motivated and described for representing defaults in specifications. The formalism is called Ordered Theory Presentations. The ability to represent defaults narrows the gap between a customer 's initial requirements and a formal specification, and supports reuse on both a small and a large scale. We illustrate the issues throughout with reference to the lift example. We also consider the application of the formalism to specification revision. 1 Introduction Imagine specifying a lift system. There is a lift, with n buttons and n indicator lights inside, and there are doors. The buttons inside the lift are for requesting where the lift goes, and the indicator lights register such requests. There are floors, each with two buttons and indicator lights (one for requesting to go up and one for down). The indicator lights switch on in response to button pressings and off when the lift arrives at a floor; and the lift goes from floor to floor depending on the state of the ligh...

### Citations

1457 |
A logic for default reasoning
- Reiter
- 1980
(Show Context)
Citation Context .... A full investigation is given in [11]; here we summarise our findings. We have analysed several default systems, and found them wanting from our point of view. For example, Reiter's `Default Logic' =-=[10]-=- represents defaults as rules of inference which interfere with the underlying logic, and cannot cope with the modalities of MAL. Conflicting defaults are handled by coding their precedence as consist... |

836 |
Circunscription – A form of non-monotonic reasoning
- McCarthy
(Show Context)
Citation Context ...precedence as consistency checks, as the specificity principle cannot be used directly. Also, Reiter's system enjoys insufficiently many of the formal properties of [7]. McCarthy 's `Circumscription' =-=[6, 8]-=-, which has better formal properties of the kind described in [7], fares better from our point of view, representing defaults as ordinary first order sentences. But it is still unclear how modalities ... |

325 | Computing circumscription
- Lifschitz
- 1985
(Show Context)
Citation Context ...precedence as consistency checks, as the specificity principle cannot be used directly. Also, Reiter's system enjoys insufficiently many of the formal properties of [7]. McCarthy 's `Circumscription' =-=[6, 8]-=-, which has better formal properties of the kind described in [7], fares better from our point of view, representing defaults as ordinary first order sentences. But it is still unclear how modalities ... |

201 |
Logics of Time and Computation
- Goldblatt
- 1987
(Show Context)
Citation Context ... example, the fact that the action a if executed in a state satisfying condition OE results in a state satisfying / is expressed by the axiom OE ! [a]/: There are many accounts of modal action logics =-=[3, 4, 5, 14]-=-. We now describe a simple version which we refer to as mal below. A component within a specification is, in logical terms, a signature together with a theory presentation over the signature. A mal si... |

152 |
General patterns in nonmonotonic reasoning
- Makinson
- 1994
(Show Context)
Citation Context ...faults are handled by coding their precedence as consistency checks, as the specificity principle cannot be used directly. Also, Reiter's system enjoys insufficiently many of the formal properties of =-=[7]-=-. McCarthy 's `Circumscription' [6, 8], which has better formal properties of the kind described in [7], fares better from our point of view, representing defaults as ordinary first order sentences. B... |

80 | On inheritance hierarchies with exceptions
- Etherington, Reiter
- 1983
(Show Context)
Citation Context ... axiom, M(press k ) fl :lit k . But [press k ]lit k is an axiom, so M(\Delta) fl [press k ]lit k and so M(press k ) fl lit k , a contradiction. This principle is well-known in artificial intelligence =-=[2, 15]-=-. It applies in this case because statement 4 is about lifts (i.e. it is in the lift object), while statement 5 is about buttons (it is in the button object). The structure of the lift specification s... |

34 | Implicit Ordering of Defaults in Inheritance Systems
- Touretzky
- 1982
(Show Context)
Citation Context ... axiom, M(press k ) fl :lit k . But [press k ]lit k is an axiom, so M(\Delta) fl [press k ]lit k and so M(press k ) fl lit k , a contradiction. This principle is well-known in artificial intelligence =-=[2, 15]-=-. It applies in this case because statement 4 is about lifts (i.e. it is in the lift object), while statement 5 is about buttons (it is in the button object). The structure of the lift specification s... |

33 | Defaults and revision in structured theories
- Ryan
- 1991
(Show Context)
Citation Context ... \Gamma \Gamma \Gamma \Gamma \Gamma` n i=1 (floor i ! :lit i ) Figure 1: Part of the OTP for the lift 4 Ordered theory presentations The concept of ordered theory presentation was first introduced in =-=[12]-=-, under the name `structured theory'. Since then the definitions and notations for OTPs have been improved and new results have been obtained. See also [11]. The present paper applies the cumulation o... |

32 | Sharing actions and attributes in modal action logic
- Ryan, Fiadeiro, et al.
- 1991
(Show Context)
Citation Context ... example, the fact that the action a if executed in a state satisfying condition OE results in a state satisfying / is expressed by the axiom OE ! [a]/: There are many accounts of modal action logics =-=[3, 4, 5, 14]-=-. We now describe a simple version which we refer to as mal below. A component within a specification is, in logical terms, a signature together with a theory presentation over the signature. A mal si... |

31 | Representing defaults as sentences with reduced priority - Ryan - 1992 |

30 |
Describing, structuring and implementing objects
- Fiadeiro, Maibaum
- 1991
(Show Context)
Citation Context ... example, the fact that the action a if executed in a state satisfying condition OE results in a state satisfying / is expressed by the axiom OE ! [a]/: There are many accounts of modal action logics =-=[3, 4, 5, 14]-=-. We now describe a simple version which we refer to as mal below. A component within a specification is, in logical terms, a signature together with a theory presentation over the signature. A mal si... |

20 | Applications of Circumscription to formalising Common Sense Knowledge - McCarthy - 1986 |

12 |
Towards object calculi
- Fiadeiro, Maibaum
- 1991
(Show Context)
Citation Context |

10 |
Ordered Presentations of Theories: Default Reasoning and Belief Revision
- Ryan
- 1992
(Show Context)
Citation Context ...theory presentation was first introduced in [12], under the name `structured theory'. Since then the definitions and notations for OTPs have been improved and new results have been obtained. See also =-=[11]-=-. The present paper applies the cumulation of this work to the problem at hand, namely, the representation of defaults and revisions in specifications. Let M be the set of interpretations as described... |