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Proscriptive codes and emergent urban structure

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  • Christopher Miller
    A series of posts on the CoolTowns blog this week point to some very interesting work on how a set or proscriptive (as opposed to prescriptive) rules from
    Message 1 of 1 , Dec 31, 2008
      A series of posts on the CoolTowns blog this week point to some very
      interesting work on how a set or proscriptive (as opposed to
      prescriptive) rules from early mediterranean times lead to emergent
      urban structure typical of many mediterranean towns:



      The blog, from a Montreal based, recently graduated architecture
      student, that summarises the work describing these codes:


      (Images are of course stripped away by the Yahoo! Groups software, so
      following the link gives you the best read.)

      Decoding paradise - the emergent form of Mediterranean townsDecember
      21, 2008 · 3 Comments


      Serifos in Greece

      Until very recent times, a study entitled Julian of Ascalon’s Treatise
      of Design and Construction Rules From Sixth-Century Palestine might
      have been categorized somewhere in-between ancient history and
      archeology of architecture, if not relegated to the dusty shelves of
      legal scholarship. Although it deals with one of the most sought-after
      secrets of architecture, how to build the charming Mediterranean towns
      of Greece, Spain, North Africa, the Near East and many other places,
      this is not immediately obvious from the content of the treatise. The
      reason for this is that the treatise does not so much describe the
      form of the town as the process for building it, and the process turns
      out to be emergent. Unless the reader makes the link from process to
      form, the rules described will make no more sense than the rules for a
      cellular automaton out of context.

      It is tragic that enormous amounts of resources have been spent
      attempting to recreate the Mediterranean town with no clue as to the
      underlying source of its complexity. Montreal itself has the world
      famous Habitat 67, a confusing pastiche of the memories that architect
      Moshe Safdie brought back from his land of birth, which he had in
      common with Julian of Ascalon. Habitat 67 was intended to be a low-
      cost solution to housing, but it never was taken seriously as a model
      for urban habitat, and its current untrendiness spares it from being
      labeled fake complexity. That an attempt to emulate the architecture
      of some of the poorest people of previous centuries would result in an
      expensive failure testifies to the inadequacy of modern production
      processes, but also of the wealth inherent in those simple traditional
      production processes. The beauty resulting from large aggregations of
      simple buildings has turned many towns into tourist destinations.
      There is value in process.

      The complexity demonstrated by the constructions of pre-modern
      civilizations may be a direct consequence of their material poverty.
      Most people will claim that the loss of building quality is a result
      of culture, and so we must change our own culture through education.
      That is not a complete answer. Cultures are stored in information
      technologies and media. The modern era coincides with the invention of
      printing, making it possible for the first time to reproduce
      information in large quantities at low costs. As information
      technologies have progressed and become more affordable, building
      processes have become increasingly dependent on large amounts of
      descriptive information, with blueprints describing in every minute
      detail how to compose a building. And now that CAD software can
      describe and store nearly limitless information, whole new forms of
      buildings have become possible.

      All of this progress has only enabled builders to become lazier with
      information. Pre-modern builders, limited to oral communication and
      their brains to hold information, had to employ very sophisticated
      means of information compression to communicate and simply remember
      their cultures. This lead them to rely on simple processes the likes
      of which are behind the complexity in fractal geometry and cellular
      automata to build their environments - very short sequences of
      information that can be utilized to generate fully complex forms.
      Christopher Alexander even used as an example, in The Nature of Order,
      the production of a boat that had been coded into a song that the
      builders recited while creating the boat, adding a mnemotechnical
      aspect to the storage of cultural information that was essential to
      pre-modern survival.

      Without knowing how traditional cultures were stored, we had no idea
      how to inspire ourselves from them. Modern and post-modern architects
      attempted in vain to imitate traditional building using their own,
      lazy information technologies, and succeeded only in building pastiche
      of complexity. The breakthroughs in complexity theory of the past
      decades finally gave us the opportunity to decode the mysteries of
      historic building cultures by showing us what kind of information to
      search for. What was right in front our noses suddenly becomes deeply

      It is to his great credit that Besim S. Hakim went looking
      specifically for the source of the emergent forms of Mediterranean
      towns in treatises of building laws. From his study of the treatise of
      Julian of Ascalon, but also of those of Muslim scholars around the
      Mediterranean, he was able to identify the underlying process that
      generates the complex morphology all towns of the region have in
      common, and that so many have sought to imitate. It is no exaggeration
      to call this pioneering work in complexity.

      The space of Hakim’s search began in the Islamic world, with the
      treatise of Ibn al-Rami from Tunis in circa 1350. Tracing the origins
      of the practices described in the treatise, references to treatises
      written in Egypt, Arabia, Tunisia and Andalusia in previous centuries
      were researched until the treatise of Julian of Ascalon was uncovered.
      Written in Palestine to describe the local building customs in order
      to provide the Byzantine empire with an improved legal system, this
      particular treatise’s value is its longevity. After propagating
      throughout Greek civilization as part of a general book of laws (the
      Hexabiblos), its authority was invoked in decisions dating as recently
      as the 19th century. Hakim infers the origins of these shared
      practices, and the shared morphology of regions as far apart
      culturally, linguistically and geographically, as Andalusia, Greece
      and Palestine, to customs from ancient Babylonian civilization that
      had spread to the Eastern Roman Empire.

      The goal shared by these treatises is a definition of urbanism as
      relevant today as it was in Babylon:

      The goal is to deal with change in the built environment by ensuring
      that minimum damage occurs to preexisting structures and their owners,
      through stipulating fairness in the distribution of rights and
      responsibilities among various parties, particularly those who are
      proximate to each other. This ultimately will ensure the equitable
      equilibrium of the built environment during the process of change and
      growth. (Hakim, Mediterranean urban and building codes: origins,
      content, impact, and lessons, p. 24)

      Here we see what the underlying error of Habitat 67 was. It was
      designed as a single static building imitating a process that made a
      living tissue out of many individual acts of simple building. The
      codes of the Mediterranean treat the town as a living, whole structure
      in movement that must be preserved while it achieves equilibrium with
      a changing environment and society.

      Perhaps the most relevant conclusion of this research is the
      identification of proscriptive and prescriptive rules for building.

      Proscription is an imposed restraint synonymous with prohibition as in
      ‘Thou shalt not’, for example, you are free to design and manipulate
      your property provided you do not create damage on adjacent
      properties. Prescription is laying down of authoritative directions as
      in ‘Thou shalt’, for example, you shall setback from your front
      boundary by (x) meters, and from your side boundaries by (y) meters
      regardless of site conditions. Byzantine codes in many instances
      included specific numeric prescriptions, unlike their Islamic
      counterparts that tended not to include them. (Hakim, Mediterranean
      urban and building codes: origins, content, impact, and lessons, p. 26)

      A prescription would be a rule that defines in detail what to do in a
      given situation. A proscription is a template for defining
      prescriptive rules, a pattern for a rule. Muslim scholars provided
      mainly proscriptions, but Julian of Ascalon’s treatise was highly
      prescriptive. Julian was describing in details the local building
      codes with the idea that they would be used to devise proscriptive
      rules for the empire. By accident these prescriptive rules became law
      and remained in force for centuries until their inability to deal with
      society or physical conditions radically different from sixth century
      Palestine made them obsolete. Although it means the codes failed to
      deal with changing circumstances, this gives us the chance to bridge
      the gap between the physical structure of built towns and the rules
      that generate them.

      The concept of proscriptive rules also helps explain why so many
      different cultures with specific structural typologies can generate
      such similar morphology. Hakim uses as an example the problem of
      views. The Greeks were preoccupied with views of the sea, and their
      prescriptive rules obliged the preservation of view corridors in new
      constructions. Muslims, on the other hand, were preoccupied with the
      preservation of privacy and the prevention of intrusive views from one
      property to another. This would have very different results
      structurally, however those two prescriptive rules are based on the
      same underlying proscription. Local customs and culture could
      therefore be translated into prescriptive rules using the
      proscriptions inscribed in building treatises and the emergent
      morphology of those proscriptions would be symmetric from one culture
      to the next, while being fully adapted to local conditions.

      Another significant fact that strikes out from these treatises is the
      importance of relationships between neighbors. The Julian of Ascalon
      treatise describes how to literally embed houses into each other,
      ultimately making them one continuous, somewhat random building
      created through iterated steps. But most importantly by proscribing
      rules as relevant to a neighborhood, Mediterranean urbanism avoids the
      problem of the absolutist, dare I say “Cartesian” rules of modern
      planning that are relative to the precisely subdivided lot the
      building is on. Hakim shows the wastefulness of latter rules in a
      comparison of the old town of Muharraq in Bahrain with a new
      subdivision from modern Muharraq

      The town on the left was generated using proscriptions based on
      neighbors, while the subdivision on the right used absolute rules
      planned with the subdivision. Notice that the configurations on the
      right waste much of the space in order to achieve a strictly
      Cartesian, grid-like morphology that no doubt looks orderly to the

      The last item of significance, and perhaps the most revolutionary, is
      how the proscriptions extracted by Hakim are similar in nature to the
      rules that Stephen Wolfram described to generate emergent complexity
      with cellular automata. He himself follows a proscription/prescription
      system, where the proscription is for example the 2 color, one-
      dimension elementary cellular automaton that made him famous, for
      which there exist 256 different prescriptive rules of neighborhood,
      some of which grow in time to make two-dimensional chaotic fractals.
      Some urban complexity researchers such as Michael Batty have been
      playing with cellular automata trying to reproduce urban form, but
      their efforts have taken them on the wrong track. The codes of
      historic towns behave in the same manner as a cellular automaton. This
      should be the focus of their research.

      Whatever the potential for research, the proscriptions discovered by
      Besim S. Hakim are still relevant today and can be used to create the
      prescriptions that we need to implement an emergent urbanism relevant
      to the problems of today, that is to say the creation of a sustainable
      city and living urban tissue out of the vast urban fabric of suburban
      sprawl. Hakim has so far focused his work on the regeneration of
      historic neighborhoods by restoring the generative codes that produced
      them, but there is a vast potential to expand his work to non-historic
      neighborhoods that are in dire need of new life.


      Four regions, four cultures, one shared process generating a symmetric










      Besim S. Hakim - Generative processes for revitalising historic towns
      or heritage districts

      Besim S. Hakim - Julian of Ascalon’s Treatise of Construction and
      Design Rules from Sixth Century Palestine

      Besim S. Hakim - Mediterranean urban and building codes: origins,
      content, impact, and lessons

      and don’t forget to look at Besim S. Hakim’s website.


      The URL links from Mathieu Hélie's blog:

      Besim S. Hakim - Generative processes for revitalising historic towns
      or heritage districts:


      Besim S. Hakim - Julian of Ascalon’s Treatise of Construction and
      Design Rules from Sixth Century Palestine:


      Besim S. Hakim - Mediterranean urban and building codes: origins,
      content, impact, and lessons:


      and don’t forget to look at Besim S. Hakim’s website:



      Christopher Miller
      Montreal QC Canada

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