Demonstration of hyper-programming in Java

We demonstrate the use of a hyper-programming system to build persistent Java applications in PJama, an orthogonally persistent version of Java. This allows program representations to contain type-safe links to persistent objects embedded directly within the source code. The potential benefits include greater potential for static program checking, improved efficiency, and reduced programming effort.Postprin

Compiler Verification and Compiler Architecture

AbstractWe study issues in verifying compilers for modern imperative and object-oriented languages. We take the view that it is not the compiler but the code generated by it which must be correct. It is this subtle difference that allows for reusing standard compiler architecture, construction methods and tools also in a verifying compiler.Program checking is the main technique for avoiding the cumbersome task of verifying most parts of a compiler and the tools by which they are generated. Program checking remaps the result of a compiler phase to its origin, the input of this phase, in a provably correct manner. We then only have to compare the actual input to its regenerated form, a basically syntactic process. The correctness proof of the generation of the result is replaced by the correctness proof of the remapping process. The latter turns out to be far easier than proving the generating process correct.The only part of a compiler where program checking does not seem to work is the transformation step which replaces source language constructs and their semantics, given, e.g., by an attributed syntax tree, by an intermediate representation, e.g., in SSA-form, which is expressing the same program but in terms of the target machine. This transformation phase must be directly proven using Hoare logic and/or theorem-provers. However, we can show that given the features of today's programming languages and hardware architectures this transformation is to a large extent universal: it can be reused for any pair of source and target language. To achieve this goal we investigate annotating the syntax tree as well as the intermediate representation with constraints for exhibiting specific properties of the source language. Such annotations are necessary during code optimization anyway

A Casual Tour Around a Circuit Complexity Bound

I will discuss the recent proof that the complexity class NEXP (nondeterministic exponential time) lacks nonuniform ACC circuits of polynomial size. The proof will be described from the perspective of someone trying to discover it.Comment: 21 pages, 2 figures. An earlier version appeared in SIGACT News, September 201

Lincoln-proposed schedule modifications covering 8-month period for installation and test of first direction center

Includes: introduction; schedule requirements; related schedules; and status of the direction center on 1 March 1957.Memorandum proposing to reduce by 14 weeks that time requirement scheduled by the ADES Engineering-Installation Phasing Subcommittees for the first SAGE installation, test, and program checking period