Title:
Reasoning About Conditional Progress Properties
Reasoning About Conditional Progress Properties
Authors
Calvert, Kenneth L.
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Abstract
In some otherwise attractive formalisms, it can be difficult or even impossible
to specify progress in such a way that a component of a distributed system can
be proved correct independent of its environment. This problem arises because
the nested dependencies between the component and its environment cannot be
conveniently expressed in the formalism. A typical example is a communication
protocol, which is supposed to provide reliable data transfer even over
channels that are unboundedly lossy: the channels only deliver messages if the
protocol transmits them often enough, while the protocol only guarantees
reliable service if the channels deliver sufficiently many messages. This paper
investigates the extent to which such progress specifications can be dealt with
using predicate calculus and a single temporal operator (leads-to) having a
simple proof theory. It turns out that under the proper semantic
interpretation, many progress specifications expressing complex dependences
can be represented using certain boolean combinations of leads-to properties.
By adding two simple inference rules to an existing proof theory, we obtain a
(relatively) complete theory for a large class of conditional progress
properties, without the complexity of the full temporal logic; such a theory
can be used with various compositional specification formalisms. Based on the
results, an approach to specification of protocol progress is outlined and
illustrated with an example.
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Date Issued
1994
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246644 bytes
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Text
Resource Subtype
Technical Report