Geoffrey Brown – författare

Current research into formal methods for hardware design is presented in the papers in this volume. Because of the complexity of VLSI circuits, assuring design validity before circuits are manufactured is imperative. The goal of research in this area is to develop methods of improving the design process and the quality of the resulting designs. The major trend apparent at the workshop is that researchers are rapidly moving away from post hoc proof techniques with their great expense. A number of papers were presented that dealt with problems of synthesizing correct circuits and of designing with the goal of verification. Researchers are also beginning to deal with the theoretical issues of reasoning about concurrent systems and asynchronous systems, and to introduce new logical tools such as constructive type theory and category theory. Most of the research reported was performed in the United States.

In the dozen years since the first edition appeared, there has been a great advance in understanding of the Earth's deep interior. This is not because there have been breakthroughs in understanding, or even many changes of ideas, but largely because of many small advances, often the result of improved tech­ niques. This has led to a complete revision of the book. For instance, we have a much better idea of how the cloud of gas that formed the Solar Nebula evolved into the Sun and the planets, and of the chemical processes that accompanied its evolution and determined the mix of elements in the Earth. We have a better understanding of convection and how plates are an essential part of it, and how it is accompanied by chemical processes that have extracted the materials to build continents. Although the major variation within the Earth is radial, improved geophysical and geochemical techniques have made progress in investigating and under­ standing the lateral heterogeneities, and it is encouraging that when geochemists and geophysicists talk about lateral heterogeneities they can sometimes be referring to the same thing. Plumes have become very fashionable as the cause of hot-spot magmatism and associated geochemical anomalies, probably origi­ nating at the base of the mantle (though clear evidence for their existence is lacking).

In the dozen years since the first edition appeared, there has been a great advance in understanding of the Earth''s deep interior. This is not because there have been breakthroughs in understanding, or even many changes of ideas, but largely because of many small advances, often the result of improved tech­ niques. This has led to a complete revision of the book. For instance, we have a much better idea of how the cloud of gas that formed the Solar Nebula evolved into the Sun and the planets, and of the chemical processes that accompanied its evolution and determined the mix of elements in the Earth. We have a better understanding of convection and how plates are an essential part of it, and how it is accompanied by chemical processes that have extracted the materials to build continents. Although the major variation within the Earth is radial, improved geophysical and geochemical techniques have made progress in investigating and under­ standing the lateral heterogeneities, and it is encouraging that when geochemists and geophysicists talk about lateral heterogeneities they can sometimes be referring to the same thing. Plumes have become very fashionable as the cause of hot-spot magmatism and associated geochemical anomalies, probably origi­ nating at the base of the mantle (though clear evidence for their existence is lacking).