stackdump

This blog post is NOT about LLMs!! The term Model is barely mentioned now-a-days without a prefix — as “Large Language Models” have reshaped the technical landscape.

A model is an abstract representation of a process that is composed of both behaviors (actions) and attributes (data). A good model allows for a system to be more predictable and easier to understand. A great model can also reduce the code complexity of a program.

Building Functional Models

Functional programming philosophy tells us that any problem can be solved via a reductionist approach: the developer decomposes a problem into functions, and then re-composes those functions into a solution.

This same paradigm is can be formally applied using petri-net models. First, we model the problem to be solved as a series of events. Then, by linking actions with input and output states, we compose these events into a full solution.

Net Analysis

Petri-nets are a formal analysis tool providing a formal foundation at design time, but we can also use them to make assertions about our program at runtime.

One useful attribute for analysis is reachability:

Given an input state, can the petri-net state machine be transformed into a target state?

Another testable property is boundedness:

Does this net model a closed system? Can a given place ever hold more than N tokens? Does the system ever create or destroy tokens?

The last property we hilight is liveness:

Can the network reach a state where no transformations are possible? under what conditions does the network reach this halting state?

Many of these properties can be analyzed through simulation. The petri-net itself is an executable schema. Pflow leverages this ability to interact with a model as a way to let users perform these checks simply by running model in a browser.

Conclusion

Building models into our code can improve design and the execution. Small models are comprehensible a user and developer alike. For a software developer, using a state machine for problem solving applies rigor at both design-time and program runtime. As a user, models can inform and educate about the state of a running process while interacting with a program. Check out the resources below how to use models in your code:

Visit https://pflow.xyz/docs-petri-net-101 to learn more about petri-nets, or try to compose one yourself using the editor https://pflow.xyz/editor.