About LPA & VisiRule Applications

LPA: 39 years in applied AI

VisiRule is 100% owned and developed by Logic Programming Associates Ltd (LPA).


LPA is a small, private UK company specialising in Artificial Intelligence software solutions. LPA was founded back in 1981, and LPA staff, many of whom joined in the 80s, have extensive experience in designing and implementing practical AI software solutions. LPA engineers have advised and consulted on numerous AI projects.


Read how LPA was recognized as Artificial Intelligence Innovators by CV Magazine.


In 2019, LPA joined the Barclays Eagle Labs LawTech incubator in Notting Hill, London. Go and read the full press release.


In 2020, LPA launched a VisiRule Analytics module, and presented its new ChatBot delivery module which incorporates VisiRule decision tree logic with FAQ KB access.

LPA Delivers A Range Of Software Development Tools For Both Programmers And Non-Programmers

microProlog Spectrum.jpg

History of LPA

LPA is the leading supplier of Prolog compiler systems for PCs and offers a wide range of integrated AI products based on LPA Prolog for Windows. Prolog was one of the first computer programming languages to be associated with Artificial Intelligence; the other being LISP. Prolog is still being discovered by even now by new programmers, and there is a lot of publicly available code for solving all sorts of mathematical and logical problems.

In 1981, LPA was formed to exploit the results emerging from the logic programming research team of Prof. Bob Kowalski at Imperial College, London. Amongst those making the transition from academia to industry were Brian D Steel and Clive Spenser both still with the company. They were later joined by Alan Westwood.


LPA's initial product, micro-PROLOG, was the world's first Prolog system for small machines and was implemented on many micro-computers of the time. micro-PROLOG was years ahead of its time but severely restricted by the memory limitations of 8-bit chips i.e. 64K RAM. LPA has since built products on 16-bit, 24-bit and 32-bit PCs and now on modern 64-bit cloud based servers.

In 1985, LPA helped organize the Practical Application of Prolog event which featured presenters from Microsoft, IBM, etc. Peter Reintjes gave an inspiring tutorial on Prolog for Software Engineering.

Since then, LPA has continued to develop and sell advanced software tools, and is firmly established as a leading supplier of commercial software products and solutions in the areas of Expert Systems and Artificial Intelligence. LPA has acquired a wealth of expertise in developing and delivering disruptive applications.

LPA's current range of AI tools support companies who want to build, test and deliver intelligent applications and embedded components.

Business Integrity & Contract Express

Between 1996 and 1998, based on work co-funded through a DTI Smart award, LPA developed ScaffoldIT, a tool for building dynamic documents and intelligent web sites. This technology, built using the LPA Prolog engine and associated ProWeb Server, was able to generate complex, personalised documents such as insurance policy schedules, legal contracts, and complex sales proposals, on the Web.

To exploit this research, LPA partnered with a small London law-firm, Tarlo Lyons. They set up a new company, named Business Integrity Ltd, BIL, with Clive Spenser as a Founding Director. In 2001, Legal Technology Insider reported the initial BigLaw sales of DealBuilder (as the product was then known).


The LPA software stack provided a solid and robust basis for Contract Express, and it became adopted by leading law firms such as Cliffords, Linklaters, as well as corporates such as Cisco and Microsoft. By 2012, Contract Express was being used for internal use, client facing projects and external Marketing Showcases - such as CooleyGo and Wilson Soncini's Term Sheet Generator. Jeff Thomas et al identified 14 firms offering start-up documentation using document automation tools.

As a result of the commercial success of Contract Express, BIL was acquired by Thomson Reuters in 2015. Partners and GCs trust Contract Express because lawyers are able to quickly and accurately automate and update their legal templates in Word without requiring IT specialists to convert them into programs.


This philosophy of self-service resonates with VisiRule. Both products allow non-programmers to create solutions with web-based question and answer sessions. Much of the underlying LPA software stack, that was initially used to create DealBuilder, and then later Contract Express, now forms the basis of VisiRule.

Linklaters buy DealBuilder licence

LPA Customer Applications

ErbRechner (Lexis Nexis Austria)

ErbRechner is an inheritance calculation tool for lawyers. Key questions, such as unworthiness, can only be answered by a professional. The lawyer can record all assets, liabilities, estate, donations and all the heirs, and the application will calculate the inherited and compulsory portions for all heirs both as quotas and the actual amount. You can read all about ErbRechner here!.

History of VisiRule

In 2004, LPA launched VisiRule, a graphical software tool which lets business users draw and deliver decision support systems, rather than have to engage programmers to write code for them. VisiRule has been extended and enhanced since then and used in many different projects ranging from machine diagnostics and fault finding to knowledge management and the automated generation of personalised financial advice and legal guidance.

VisiRule allows non-technical business users such as lawyers, accountants, tax advisers, healthcare professionals and field service agents, to develop and deliver decision support applications.

VisiRule was initially launched as a Windows desktop application but the run-time delivery was moved to the Web to support cloud-based deployment. Mobile phone delivery then followed as the popularity of smartphones grew. Browser-based authoring via VisiRule365 was added in 2018 along with FastChart integration with Machine Learning.

Prüfung der Geschäftsfähigkeit


This Lexis 360® tool is aimed at lawyers, and leads with questions purposefully through all the many regulations and exceptions and provides specific answers as to whether a dubious legal transaction (in terms of age or decision-making ability) is effective.

You can go try out Geschaeftsfaehigkeit here!

prüfschema screen


LPA/VisiRule is part of the EMDS.. 


The Ecosystem Management Decision Support (EMDS) system is a state-of-the-art modeling framework that supports environmental decision analysis and planning. EMDS integrates the latest technology from geographic information systems (GIS) as well as logic-based reasoning and a variety of modeling technologies. This provides explicit, practical decision support for strategic and tactical planning as well as adaptive management. Because EMDS is a generic solution framework, it can be applied to an extremely broad array of problems at virtually all spatial scales.



AllerGenius is an expert system for the interpretation of allergen arrays from Phenomix. Precision medicine (PM) is changing the scope of allergy diagnosis and treatment. The advent of low-cost widely available allergen array tests has lead to the need for the expert interpretation of the various markers.

The complexity of molecular allergy historically confined the interpretation of these tests to a small number of highly skilled allergists. AllerGenius allows allergists to access the most current and specialist interpretation of allergen arrays for their patients. Less skilled allergists can benefit from modern technology associated with a complete and dedicated interpretation system. 
Expert reports are generated in multiple European languages including Italian, Russian, Croatian and German.

      In my many years of software development, this is the first time that things were better than expected! Working with the LPA team of engineers and its software has been a pleasure. They have managed not to just to meet my current needs but anticipate most of my future requirements. As such, the core software infra-structure for AllerGenius has remained intact and largely untouched for several years and through several incarnations of the product.

Giovanni Melioli, MD Phenomix Ltd Genova, Italy


PALTESTER is a desktop software application from ESROE developed using LPA Prolog that enables the analysis of the identification performance of an automatic Radar ESM system. It was created to provide military analysts with tools to analyse the identification performance of ESROE’s THORONDIR emitter identification software used in operational Radar ESM systems.

Paltester screen


CASSANDRA is a platform developed by KnowGravity in Zurich, Switzerland. It is assistant-based and guides the users through their tasks in business, systems and software engineering. It analyses project data from many familiar UML®-based CASE tools, generates the appropriate questions or proposes the next steps in order to move the process forward.

By turning UML models into precise xUML models (Executable UML), it becomes possible to define an environment in which such implementation-independent analysis models can be executed without considering technical details of the target platform. 


InFlow is a leading Social Network Analysis tool from OrgNet which performs network analysis AND network visualization in one integrated product -- no passing files back and forth between different programs like other tools. What is mapped in one window is measured in the other window -- what you see, is what you measure. InFlow excels at what-if analysis -- change the network, get new metrics -- just 2 clicks of the mouse. You do not need to be an expert in statistics to use InFlow.

InFlow SNA Picture

InFlow & Transmission Network Analysis (TNA)


You can read how InFlow has been used to model network transmission for contagious diseases. Transmission Network Analysis (TNA) is best applied early in an outbreak before a mass outbreak sets in to a local area. Tracking the early cases provides great insight into how, when, and where the contagion is spreading. Data collection is difficult but always proves worthy to the understanding and management of the outbreak.