Two Kinds of Patterns

Did you know that you use patterns every day? It’s a very powerful mechanism and much more powerful when they are explicit and known.

A pattern describes a proven solution for a problem. Every experienced engineer has a huge set of patterns. Think about your daily work. If you must solve a problem that you’ve solved successfully before, you will remind your solution and apply it again. If you describe your solution in a general and reusable way, you’ve made your experience explicit and persistent. Voila! You’ve found a pattern.

Christopher Alexander described patterns for building architectures (his pattern book), Erich Gamma & Co. described patterns for software engineering (their pattern book) and Robert Cloutier describes patterns for systems engineering (his work).

I’d like to put a focus on another kind of a pattern. In system modeling the graphical representation of the model data is an important part. It definitely makes a difference how you present your data. The human brain looks for graphical patterns and not for all the little details. That makes life much easier. For example you can change the letters in a text while keeping the pattern structure and you could still read the text:

Mdoel Baesd Setmsys Ennneigierg mekas my procjets mroe ecffetive.

Cool, isn’t it. Similar things happen when you look at SysML diagrams. You’ll see graphical patterns. Unfortunately such patterns are not well known and described. Here’s a huge potential to be more effective.

For example it makes a difference if you layout a product tree in a block definition diagram top-down, bottom-up or in a non-tree layout style.

Product tree (top-down)

Product tree (bottom-up)

Product tree (non-tree style)

I prefer the top-down layout. It emphasizes the break down of the product (Product Breaddown Structure (PBS)).

I know that there is lots of information about human pattern reception in general. But I know no paper or book that combines those results with system modeling. I appreciate any hint.

Finally some guidelines/facts:

• Typical reading direction is from top to down, from left to right. It is different in some cultures.
• A diagram should not contain more than 7 main elements.
• A diagram should have a printable layout (A4 or letter format).