Trylock, a case for temporal logic and eternity variables

An example is given of a software algorithm that implements its specification in linear time temporal logic (LTL), but not in branching time temporal logic (CTL). In LTL, a prophecy of future behaviour is needed to prove the simulation. Eternity variables are used for this purpose. The final phase of the proof is a refinement mapping in which two threads exchange roles. The example is a software implementation of trylock in a variation of the fast mutual exclusion algorithm of Lamport (1987). It has been used fruitfully for the construction of software algorithms for high performance mutual exclusion

Using eternity variables to specify and prove a serializable database interface

Eternity variables are introduced to specify and verify serializability of transactions of a distributed database. Eternity variables are a new kind of auxiliary variables. They do not occur in the implementation but are used in specification and verification. Elsewhere it has been proved that eternity variables in combination with history variables are semantically complete for proving refinement relations. An eternity variable can be thought of as an unknown constant that is determined by the behaviour (execution sequence). In the specification of the database, one eternity variable is used to enforce serialization. In the verification, an additional eternity variable is needed for the connection of the local data with the shared database. The formalism is based on linear-time temporal logic, but the analysis of behaviours is completely reduced to the next-state relation together with progress arguments using variant functions. Forward invariants (inductive predicates) are complemented with other, so-called backward, invariants. The proof has been verified with the first-order theorem prover NQTHM to give additional confidence in the result and in the feasibility of the approach.

Using Eternity Variables to Specify and Prove a Serializable Database Interface

Eternity variables are introduced to specify and verify serializability of transactions of a distributed database. Eternity variables are a new kind of auxiliary variables. They do not occur in the implementation but are used in specification and verification. Elsewhere it has been proved that eternity variables in combination with history variables are semantically complete for proving refinement relations

The Object of Platform Studies: Relational Materialities and the Social Platform (the case of the Nintendo Wii)

Racing the Beam: The Atari Video Computer System,by Ian Bogost and Nick Montfort, inaugurated thePlatform Studies series at MIT Press in 2009.We’ve coauthored a new book in the series, Codename: Revolution: the Nintendo Wii Video Game Console. Platform studies is a quintessentially Digital Humanities approach, since it’s explicitly focused on the interrelationship of computing and cultural expression. According to the series preface, the goal of platform studies is “to consider the lowest level of computing systems and to understand how these systems relate to culture and creativity.”In practice, this involves paying close attentionto specific hardware and software interactions--to the vertical relationships between a platform’s multilayered materialities (Hayles; Kirschenbaum),from transistors to code to cultural reception. Any given act of platform-studies analysis may focus for example on the relationship between the chipset and the OS, or between the graphics processor and display parameters or game developers’ designs.In computing terms, platform is an abstraction(Bogost and Montfort), a pragmatic frame placed around whatever hardware-and-software configuration is required in order to build or run certain specificapplications (including creative works). The object of platform studies is thus a shifting series of possibility spaces, any number of dynamic thresholds between discrete levels of a system