We present a practical and asymptotically optimal indexing structure for a versioned timestamped database with step-wise constant data. Three version operations, insertions , updates, and deletes are allowed for the present version, whereas query operations are allowed for any version, present or past. Snapshot and time-range queries can be answered optimally with this structure. As a two-level...

High capacity disks, especially optical ones, are commercially available. These disks are ideal for archiving large text data bases. In this work, we examine efficient searching techniques for such applications. We propose a unifying framework, which reveals the similarities between signature files and an inverted file using a hash table. Then, we design methods that combine the ease of inserti...

Scheme is one of only a few languages with a concise specification and formal semantics. With such a foundation it should be easy to write portable code that, without modification, runs correctly on different Scheme implementations. Yet this goal has proved elusive – there are more than fifty Schemes and writing programs that are portable between even just a few of these implementations is tedi...

Telling stories to help relieve a woman in labor may be soothing, but one must be sure to choose the right tale.

We present a sound type-basedùsage analysis' for a realistic lazy functional language. Accurate information on the usage of program subexpressions in a lazy functional language permits a compiler to perform a number of useful optimi-sations. However, existing analyses are either ad-hoc and approximate, or deened over restricted languages. Our work extends the Once Upon A Type system of Turner, ...

Aminoacyl-tRNA synthetases play a central role in protein synthesis by covalently linking the correct amino acid to the correct tRNA (1). Each aminoacyl-tRNA is then carried to the ribosome where it interacts with the cognate trinucleotide codon on the mRNA and transfers the amino acid onto a growing polypeptide chain. Work on tRNAs and aminoacyltRNA synthetases from bacteria, fungi, plants, an...

My third year of medical school, and I have finally begun my training. I am slowly learning to be a surgeon. I will open you up and search through the detritus of sickness, extirpate what is necessary, and leave in my wake a health of my own creation. There is power in that; a power that I have already glimpsed. Reaching out and calmly saying, "knife." Deliberately moving the scalpel across the...

To focus the comparison of languages for model checking and transformation on criteria that matter in practical development, there is an urgent need for more, and more realistic, case studies. In this position paper, we first present the problem of developing distributed database applications that are optimized for concurrent data access. The problem constraints are avoiding vendor lock-in, mak...