Having different BISLs tailored to each programming language allows each BISL to specify all the details of a program module's interface (how to call it) and behavior (what it does). If one has a generic interface specification language, such as VDM-SL [Jones90] [ISO-VDM96] [Fitzgerald-Larsen98], then one cannot specify all interface details. The division into two tiers allows the language used for each tier to be more carefully designed and expressive.

A good place to start is the Guttag and Horning's book [Guttag-Horning93]. (This book is sometimes called "the silver book" by Larchers.) Consider it required reading. If you find that all tough going, you might want to start with Liskov and Guttag's book [Liskov-Guttag86], which explains the background and motivates the ideas behind abstraction and specification. (See section 1.9 What is the use of formal specification and formal methods?, for more background.

According to Jim Horning (personal communication, January 20, 1998) and John Guttag (personal communication, March 28 1998): "The name was not selected at PARC (hence from the Sunset Western Garden Book), but at MIT. The project had been known informally there as 'Bicycle'." One day Mike Dertouzos [director of the MIT Laboratory for Computer Science] and John were talking on the phone.

Plan 9's approach improves generality and modularity of application design by encouraging servers that make any kind of information appear to users and to applications just like collections of ordinary files. Here are a few examples.

Larch [Guttag-Horning93] may be thought of as an approach to formal specification of program modules. This approach is an extension of Hoare's ideas for program specification [Hoare69] [Hoare72a]. Its distinguishing feature is that it uses two "tiers" (or layers) [Wing83]. The top tier is a behavioral interface specification language (BISL), tailored to a specific programming language. Such BISLs typically use pre- and postcondition specifications to specify software modules.

There are three main advantages of using Metastorage over traditional development methods that are less automated: Metastorage is capable of generating code from your component model definition in just a few seconds. It would take days or weeks to write, test and debug equivalent code manually by a human developer. This is very important to reduce the time to market your software products, especially if they are medium or large size projects.

Currently, a practitioner must attend at least one Defeat Autism Now! Conference and/or Physician's seminar in order to be added to the list of clinicians using the Defeat Autism Now! approach. The Victory Store sells autism awareness ribbons and other items. Five percent of VictoryStore's autism sales are regularly donated to ARI.

The two "tiers" used in the Larch family of specification languages are LSL, which is called the bottom tier, and a behavioral interface specification language (a BISL), which is called the top tier. This specification of program modules using two "tiers" is a deliberate design decision (see [Wing83] and [Guttag-Horning93], Chapter 3).

The main difference between LSL and a Larch BISL is that in LSL one specifies mathematical theories of the operators that are used in the pre- and postcondition specifications of a Larch BISL. Thus LSL is used to specify mathematical models and auxiliary functions, and the a Larch BISL is used to specify program modules that are to be implemented in some particular programming language.

Like VDM-SL, Z [Hayes93] [Spivey92] (pronounced "zed") is a specification language that allows both the specification of mathematical values and program modules. Like LSL, Z allows the definition of mathematical operators equationally (see [Spivey92], section 3.2.2). A Z schema is roughly comparable to an LSL trait. The main difference between Z and LSL is that in Z specifications can include state variables.

The following is adapted from a posting of Horning to the larch-interest mailing list on June 19, 1995, which was itself condensed from the preface of [Guttag-Horning93].) This project has been a long time in the growing. The seed was planted by Steve Zilles on October 3, 1973.

This question might mean one of several other more precise questions. These questions are discussed below. One question is: is there a Larch-style BISL for some particular object-oriented (OO) programming language? Yes, there are Larch-style BISLs for Modula-3 (see [Guttag-Horning93], chapter 6, and [Jones91]), Smalltalk-80 (see [Cheon-Leavens94]), and C++ (see [Leavens97] [Leavens96b]).

The Larch Shared Language (LSL) (see [Guttag-Horning93], Chapter 4, and [Guttag-Horning-Modet90]) is a language for specifying mathematical theories. LSL is a kind of equational algebraic specification language [Guttag75] [Guttag-Horning78] [Goguen-Thatcher-Wagner78] [Ehrig-Mahr85] [Futatsugi-etal85] [Mosses96] [Loeckx-Ehrich-Wolf96]. That is, specifications in LSL mainly consist of first-order equations between terms.

The Larch Prover (LP) [Garland-Guttag95] is a program that helps check and debug proofs. It is not geared toward proving conjectures automatically, but rather toward automating the tedious parts of proofs. It automates equational rewriting (proofs by normalization), but does not (by default) automatically try other proof techniques. aid the debugging of specifications (i.e.

First, Multi-tiered HSM works in many storage environments so it can augment many storage infrastructures.

Changes and updates can be deployed immediately throughout all stores with one change to the database instead of the change having to be made at each store. You have greater control over the quality of your business information.

Maybe, maybe not! Weight loss is not the goal of this approach and cannot be where our focus is. What happens with our weight will depend on our past history with dieting, how much we have damaged our metabolism, and many other factors. Those of us that start the OO approach immediately following a restrictive diet will most likely gain some weight at the beginning. But we must remember that this is weight we would have gained ANYWAY as a rebound from the diet.

This way of proceeding allows us to reduce greenhouse gases now and prepare for deeper cuts later without de-railing Canada's economy. This approach works because it forces industry to get more efficient each year so that greenhouse gases go down, even as the economy grows.

Clean. Geothermal power plants, like wind and solar power plants, do not have to burn fuels to manufacture steam to turn the turbines. Generating electricity with geothermal energy helps to conserve nonrenewable fossil fuels, and by decreasing the use of these fuels, we reduce emissions that harm our atmosphere. There is no smoky air around geothermal power plants -- in fact some are built in the middle of farm crops and forests, and share land with cattle and local wildlife.

Gasketed-joint PVC provides many advantages over other types of joining systems. The following is a brief summary: Watertight Joints: Gasketed-joint PVC water and sewer pipe joints are virtually leak-free, enabling them to easily pass post-installation air tests or leakage tests. Installation Considerations: Ease in installation is another advantage gasketed-joint PVC offers.