The Prospectus
Overview
An XML based framework supporting reasoning in the "semantic web". Generic support for defining the semantics of languages and for sound deductive reasoning in a multi-lingual context.
X-Logic is a project to develop an architecture for generic logic technologies, exploiting XML and related standards, and to catalyse the development of applications using that architecture. The architecture will provide logical foundations for the integration of diverse languages and proof technologies. The project will investigate selected areas of application, and will implement prototypes and demonstrators to prove the key ideas.
The architectural component of X-Logic provides motivating rhetoric, definitions of special terms, enunciation of key principles and supporting theory on which the architecture is based, at least one logical foundation system and some glue.
Though some (formalists) take logic to be a formal science in which syntax supplants semantics, X-Logic places semantics at the center of the universe. Three stages are envisaged in the development of methods for formally defining the semantics of languages. Monolingual, multilingual and extensible.
X-Logic Glue is the stuff which enables diverse languages and logical tools to be integrated in the solution of complex problems.
Mathematics could be said to be an intended application of X-Logic, but since it mediates in the application of logic to almost every application in science and engineering (and many elsewhere), it has a very special importance.
A small number of applications of special interest will be investigated. The most ambitious is digital controller design.
XL-namespaces are intended to combine the functions of XML-namespaces with those of logical theories and form a centerpiece of X-Logic technologies.
<image name="OpenMind.gif"></image> OpenMind is a philosophical partner to X-Logic, cohosted at X-Logic.org. It is formal analytic philosophy, exploiting X-Logic technologies and providing foundations and metatheory for X-Logic.
X-Logic is not just an OpenSource project. It is also an Open Brand.
Introduction
X-Logic is a project to develop an architecture for generic logic technologies, exploiting XML and related standards, and to catalyse the development of applications using that architecture. The architecture will provide logical foundations for the integration of diverse languages and proof technologies. The project will investigate selected areas of application, and will implement prototypes and demonstrators to prove the key ideas.
Introduction
X-Logic is an OpenSource intellectual enterprise aimed at the exploitation of modern logic on the World Wide Web in ways which maximise synergy with XML standards and tools. X-Logic.org will formulate and propound an architectural conception of X-Logic, and produce demonstrators and prototypes, of various elements of that architecture (mainly glue). X-Logic.org hopes to become the center of a family of collaborative OpenSource projects implementing logic technologies for use with XML.
Semantics
A key element of X-Logic is its contribution to the semantics of the web. X-Logic enables documents to be interpreted by associating each document with a language whose semantics has been formally defined. X-Logic will provide ways of making the association between document and language, and of defining the semantics of the language.
Inference
In the X-Logic framework reasoning is supported not just using a special class of logical languages, but in any language whose semantics is formally (possibly partially) defined. Furthermore, not only does the framework provide for integration of inferences performed by any proof tool, but it provides for the interpretation of computations by any program as logical inferences. This is accomplished by the association of specifications with programs, each of which legitimises the interpretation of computations by the program as logical inferences.
Problem Solving
The purpose of the X-Logic architecture is best captured by the venerable slogan "logic for problem solving". It is about using logic technologies to enable machines to solve a greater range of problems, including mathematical problems, engineering problems.
The W3C connection
X-Logic is an OpenSource intellectual enterprise aimed at the exploitation of modern logic on the World Wide Web in ways which maximise synergy with XML standards and tools. X-Logic.org will formulate and propound an architectural conception of X-Logic, and produce demonstrators and prototypes, of various elements of that architecture. X-Logic.org hopes to become the center of a family of collaborative OpenSource projects implementing logic technologies for use with XML.
Architecture
The architectural component of X-Logic provides motivating rhetoric, definitions of special terms, enunciation of key principles and supporting theory on which the architecture is based, at least one logical foundation system and some glue.
Rhetoric
There will be something written about why X-Logic is a good idea.
Terminology
For the rest of the architectural documentation to be intelligible some special terminology has to be introduced.
Principles
The architecture is based on certain principles. Some of these are open to debate as the project evolves, some of them are key principles which define the project (if you disagree with them you really belong in a different project).
Theory
There will be a very small amount of material which might be considered theoretical, addressing key problems such as how logical consistency is preserved while merging disparate logical systems.
Foundations
The place to put logic is at the bottom, it provides foundations. In X-Logic all other languages are given their meaning by translation (or embedding) into a simple but powerful foundational language. (though the possibility of having more than one of these is not excluded).
Glue
In X-Logic any program can be used to do inferences, what inferences a program does depends on what we know about its behaviour. The X-Logic architecture defines the kind of "glue" necessary to sew together a proof from diverse contributions.
Semantics
Though some (formalists) take logic to be a formal science in which syntax supplants semantics, X-Logic places semantics at the center of the universe. Three stages are envisaged in the development of methods for formally defining the semantics of languages. Monolingual, multilingual and extensible.
Monolingual Semantics
Define the grammar of the language, define the necessary semantic domains and values in the foundational language, then define how the one language can be interpreted in the other.
Multilingual Semantics
This is about how to interpret and reason with multiple languages at once. It is analogous to merging namespaces in XML but the namespaces have more semantic information in them. From this stage a first notion of XL-namespace emerges, and imposes constraints on the manner of formulation f semantics for the individual languages so the the merging will work.
Extensible
An important test case for X-Logic is whether it can cope with formalisation of the language of mathematics. This language (even when formalised) is not nice and tidy like programming languages. It grows over time, and though one could say that different subject areas have their own languages, there are no neat boundaries.
Glue
X-Logic Glue is the stuff which enables diverse languages and logical tools to be integrated in the solution of complex problems.
Data as Propositions
The X-Logic semantic methods and tools are intended to permit a wide range of digital information sources to be interpreted propositionally. This is the first step in its logical exploitation.
Degrees of Assurance
In order to allow the use programs which we believe to be correct, but only with a moderate or low degree of confidence claims about provability in X-Logic are qualified by caveats about the soundness of the inference methods. This gives users control over the trade-off between assurance and functionality.
Computation as Inference
Any correct computation performed on data which has a propositional interpretation is logically sound. If the input and output languages for a program are given such an interpretation, the program can then be incorporated as an X-Logic inference engine.
The Meta-Calculus
The main function of X-Logic glue is to combine inferences from diverse sources with different credentials into overall conclusions and to determine the credentials of the result. "credentials" are expressed in terms of various metrics which will be investigated as part of the architectural activities. Some of the glue may be generic with respect to the metrics involved, and other parts may be specific to particualar metrics. Assurance metrics which permit evolution to higher levels of assurance to progress alongside advances in functional capability are sought.
Mathematics
Mathematics could be said to be an intended application of X-Logic, but since it mediates in the application of logic to almost every application in science and engineering (and many elsewhere), it has a very special importance.
Application Studies
A small number of applications of special interest will be investigated. The most ambitious is digital controller design.
Digital Controller Co-Design
This problem domain combines the mathematical modelling of the controlled system with design and implementation of the digital system which provides the required control. It is an ultimate test of what might be done by logic based mathematically capable software.
Software and Web Development
It is proposed to experiment with a development paradigm in which lightwieght throwaway languages are used to describe an application, which is then generated by "semantic mappings" which interpret the descriptions in fully supported implementation languages (e.g. translate it into C).
XL Query Language
There is of course a W3C activity developing a query language for XML. Under this heading is intended an activity which tracks the W3C activity and puts together some ideas about what more could be done with a logical query language over the semantic web which X-Logic enables.
Mathematics
Mathematics may be thought of either as an application of X-Logic or as an essential extra layer of capability built on the logical foundations without which many potential applications (for example, in science and engineergine) would not be possible. X-Logic is intended to be a suitable framework for projects like QED intended to implement the formalisation of mathematics. Some existing efforts in the formalisation may be glued into the framework with little or no modification.
XL-namespaces
XL-namespaces are intended to combine the functions of XML-namespaces with those of logical theories and form a centerpiece of X-Logic technologies.
tools
Central to X-Logic is the development of techniques and tools which permit the semantics of languages to be formally defined. XL-namespaces are intended to combine the functions of XML-namespaces with those of logical theories and form a centerpiece of X-Logic technologies.
OpenMind
Formal analytic philosophy using X-Logic, rationality and deduction, X-Logic foundations.
Introduction
OpenMind applies formal methods and tools to analytic philosophical problems, explores the relationship between logic and rationality, and provides both applications of and foundations for X-Logic.
To underpin an understanding of Rationality, and as a philosophical foundations for The Semantic Web, we propose develop a new "Theory of Knowledge".
Foundation systems for formal analysis play the same role as logical foundations for mathematics but are aimed at a broader range of applications.
Open Branding
X-Logic is not just an OpenSource project. It is also an Open Brand.
What is an Open Brand?
An Open Brand is to marketing what Open Source is to hackers. Its a brand name which comes with a licence which allows anyone to use the brand without any licence fee. So if you buy into the ideas behind X-Logic, and you want to make a project of your own building on those ideas, you can use the X-Logic "brand" to quickly communicate to people who may be interested in your project that it builds on the X-Logic architecture. So like in "free software" the open in "Open Brand" means "free to use and build on".
Legally Free, Morally Constrained
Though there is no way to write it into a licence, we do request that you use the brand in good faith. If you propose to use the brand you have an obligation to get a good understanding of what it is supposed to stand for, and to use it in a manner which is consistent with what it means. If ever there were a substantial community using the brand, then you could expect to be disciplined by that ccommunity for misuse of the brand by EXPOSURE.
Open = Honest
There are several other aspects of the idea of an "Open Brand" which I don't intend to go into here (maybe, eventually, elsewhere), but this one seems to me important enought to mention now. The "Open" is also supposed to persuade you that its OK to use the brand because it is not going to be used as you may think brands usually are, to pull the wool over the eyes of potential customers and make them buy some product for reasons which are completely unconnected with its merits. The idea of Open Branding is to use brands for making Honest and truthful communications to potentially interested people about the nature of your enterprise.

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