Some years ago, in order to finish my phD, I looked for the advice of professor Roberto Moriyón, head of the computer science department (Escuela Politécnica Superior) at U.A.M. He kindly explained to me what the research activity was and what he thought could be more interesting for me.

So following Roberto's advice I met Juan de Lara who proposed to study distributed simulation protocols using graph transformation systems. I immediately became interested in the topic and started to study the so-called

*algebraic approach to graph transformation*. Actually it uses category theory. (I will comment on this and other approaches in a future post.)

Not much time passed before I started to miss a

*real*algebraic approach to graph transformation and it seemed to me that it should not be too difficult to begin with one. So I sent to Juan a new thesis proposal (in fact, seven in a few weeks) which would become the seeds of Matrix Graph Grammars. In them I included an algebraic (Boolean) characterization of

*production*(a production is just a function - or morphism or application - that transforms one graph into another graph), an initial characterization of

*sequential independence*(to what extent the order of productions inside a sequence matters) and some comments on

*parallelism*(in essence, if two productions can be applied in any order without altering the resulting graph).

We then started to develop such approach by studying

*completion*,

*coherence*,

*initial digraphs*,

*composition*,

*matching*,

*sequentialization*,

*parallelism*,

*restrictions*(

*graph constraints*and

*application conditions*) and

*reachability*. I will dedicate some posts to all of them. In some hard-to-explain sense, I feel that they are a "closed" set of results. This is basically what the Matrix Graph Grammars book include.

My intention for the future is to write a second volume, to get to complexity theory. The first few results can be found here. I need to present MGG as a model of computation, which is not foreseen to be very difficult. I'll touch on this too, but probably not soon. Some topics that I would also love to include are

*termination*and

*confluence*(basically, existence and uniqueness) but it takes time... We'll see.

Erwin Schrödinger once wrote:

**No self is of itself alone**.

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