Pattern: Mapping Forces

Summary	Alexander defines a pattern as equivalent to a diagram resolving a set of interacting and conflicting forces. Many pattern authors see the articulation of forces and relations as key to the problem description. Others claim that the notion of forces causes confusion, and is an obstacle to novice pattern writers. To resolve this conflict, groups of authors are asked to represent forces as icons. By drawing the relationship between the forces this helps illustrate the tensions that exist within a problem space.
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Problem

"An abstract pattern of physical relationships which resolves a small system of interacting and conflicting forces, and is independent of all other forces, and all other possible diagrams." Christopher Alexander, Notes on the synthesis of form, preface to the paperback edition.

In other words, without opposing forces there is no problem to be solved. But identifying forces is often a difficult task for novice pattern writers when the value of forces is a concept that takes time and experience to be fully appreciated.

Context

This pattern is used during the pattern mining workshop where a group will be discussing a number of case-stories of successful practice and identifying the key elements that form the description of the problem statement for the resultant pattern.

Solution

Ask groups of authors to undertake a force mapping exercise where they represent forces as icons. These illustrate the tensions that exist within the problem space identified across the case-stories. Authors should then build up the relationships between these by drawing links between the icons and at the simplest level indicating whether they act positively or negatively upon each other.

Related Patterns

list other patterns related to this one, under categories such as component, assisting, conflicting, uses this, etc.

Notes, Links and References

Liabilities, potential risks, extensions, expected side-effects

From http://www.hillside.net/patterns/writing/patterns.htm#B.3

B.3 Pattern: Visible Forces
Problem:

A pattern presents a solution to a problem within a context. How do you ensure that the reader understands the choice of solution?

Context:

You are writing a pattern or pattern language that is intended to convey one

of potentially several solutions to a problem. You have applied Mandatory Elements Present; you are now writing the Forces section.

Forces:

Solution:
Regardless of the style chosen for the pattern description, ensure that the forces are highly visible. This can be done by defining a meaningful "name" for each force and visually setting if off from text by making them minor headings, or by highlighting them using fonts, underlining, or other typographic techniques.

Example
This pattern language uses a "bullet list" within a Forces heading to make the forces visible. [Foote96] highlights the forces within the prose of the pattern description.

Licensing

This work is licenced under a Creative Commons Licence.