W Ross Ashby was a psychiatrist who, through books such as *Design for a brain*, was one of the pioneers of the development of systems theory (qv) in the 1950s. A particular branch of systems theory was ‘cybernetics’ – from the Greek ‘steering’ – essentially the theory of the ‘control’ of systems. This was, and I assume is, very much a part of systems engineering and it attracted mathematicians such as Norbert Weiner. For me, an enduring contribution was ‘Ashby’s Law of Requisite Variety’ which is simple in concept and anticipates much of what we now call complexity science. ‘Variety’ is a measure of the complexity of a system and is formally defined as the number of possible ‘states’ of a system of interest. A coin to be tossed has two possible states – heads or tails; a machine can have billions. Continue reading “22: Requisite Knowledge”

# 21: Research Priorities: A modeller’s perspective

**(From the Urban transformations website)**

We know a lot about cities, but there is much more that we need to know to meet future challenges effectively. My aim here is to sketch some research priorities from the perspective of the Government Office for Science Foresight Project on The Future of Cities – but much coloured by a personal position of having spent 50 years of my life on a quest to build a comprehensive mathematical model of a city that is both good science and is useful for planning and policy purposes! This narrows what I can offer but I can argue that a combination of the Foresight framework and a modelling perspective provides a good starting point. Continue reading “21: Research Priorities: A modeller’s perspective”

# 20: Back to the future – Bradford trams

This is the twentieth blog in this weekly series and after this there will be a summer break – a restart in October all being well!

Trams have a long history in British cities and are now being re-invented for a contemporary context. Electric trams started in Bradford in 1892 and ran until 1951. I was brought up in Bradford in the 1940s and so the trams were an early experience for me. There weren’t many cars at that time either. Continue reading “20: Back to the future – Bradford trams”

# 19: Territories and flows

Territories are defined by boundaries at scales ranging from countries and indeed alliances of countries) to neighbourhoods via regions and cities. These may be government or administrative boundaries, some formal, some less so; or they may be socially defined as in gang territories in cities. Much data relates to territories; some policies are defined by them – catchment areas of schools or health facilities for example. It is at this point that we start to see difficulties. Continue reading “19: Territories and flows”

# 18: Against oblivion

I was at school in the 1950s – Queen Elizabeth Grammar School Darlington – with Ian Hamilton. He went on to Oxford and became a significant and distinguished poet, critic, writer and editor – notable, perhaps, for shunning academia and running his editorial affairs from the Pillar of Hercules in Greek Street in Soho. I can probably claim to be the first publisher of his poetry as Editor of the School Magazine – poems that, to my knowledge, have never been ‘properly’ published. We lost touch after school. He went on to national service and Oxford; I deferred national service and went to Cambridge. Continue reading “18: Against oblivion”

# 17: Equations with names: the importance of Lotka and Volterra (and Tolstoy?)

The most famous equations with names – in one case by universal association – seem to come from physics: Newton’s Law of Gravity – the gravitational force between two objects is proportional to their masses and inversely proportional to the distance between them; Maxwell’s equations for electromagnetic fields; the Navier-Stokes’ equation in fluid dynamics; and E = mc^{2}, Einstein’s equation which converts mass into energy. Continue reading “17: Equations with names: the importance of Lotka and Volterra (and Tolstoy?)”

# 16: New maths needed

In the modern era, mathematical and computer models of cities have been in development for around sixty years – not surprisingly, mirroring the growth of computing power. Much has been achieved. We are pretty good at modelling the flows of people in cities for a variety of purposes and loading these trips on to transport networks; we are pretty good at estimating some activity totals at locations such as retail revenue or demand for housing. Much of this has been stitched together into comprehensive models, embracing demography and input-output economics. Continue reading “16: New maths needed”

# 15: Venturing into other disciplines

Urban and regional science – a discipline or a subdiscipline, or is it still called interdisciplinary? – has been good at welcoming people from other disciplines, notably in recent times, physicists. Can we venture outside our box? It would be rather good if we could make some good contributions to physics!! However, given that the problems we handle are in some sense generic – spatial interaction and so on Continue reading “15: Venturing into other disciplines”

# 14: Learning from history

I was recruited to a post that was the start of my urban modelling career in the Autumn of 1964 by Christopher Foster (now Sir Christopher) to work on the cost-benefit analysis of major transport projects. My job was to do the computing and mathematics and at the same time to learn some economics. Of course, the project needed good transport models and at the time, all the experience was in the United States. Christopher had worked with Michael Beesley (LSE) on the pioneering cost-benefit analysis of the Victoria Line. To move forward on modelling, in 1965, Christopher, Michael and I embarked on a tour of the US. Continue reading “14: Learning from history”

# 13: ‘Research on’ versus ‘research for’

Let us begin by asserting that any piece of research is concerned with a ‘system of interest’ – henceforth ‘the system’ (cf. Systems thinking). We can then make a distinction between the ‘science of the system’ and the ‘applied science relating to the system’. In the second case, the implication is that the system offers challenges and problems that the science (of that system or possibly also with ‘associated’ systems) might help with. In research terms, this distinction can be roughly classified as ‘research on’ the system and ‘research for’ the system. This might be physics on the one hand, and engineering on the other; or biological sciences and medicine. Continue reading “13: ‘Research on’ versus ‘research for’”