PetriNets.org

Wikipedia: “In computer science, the dining philosophers problem is an example problem often used in concurrent algorithm design to illustrate synchronization issues and techniques for resolving them. Each philosopher must alternately think and eat. However, a philosopher can only eat spaghetti when they have both left and right forks. Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher. After an individual philosopher finishes eating, they need to put down both forks so that the forks become available to others. A philosopher can take the fork on their right or the one on their left as they become available, but cannot start eating before getting both forks.”

Wikipedia: “In computer science, the dining philosophers problem is an example problem often used in concurrent algorithm design to illustrate synchronization issues and techniques for resolving them. Each philosopher must alternately think and eat. However, a philosopher can only eat spaghetti when they have both left and right forks. Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher. After an individual philosopher finishes eating, they need to put down both forks so that the forks become available to others. A philosopher can take the fork on their right or the one on their left as they become available, but cannot start eating before getting both forks.”

Wikipedia: “In computer science, the dining philosophers problem is an example problem often used in concurrent algorithm design to illustrate synchronization issues and techniques for resolving them. Each philosopher must alternately think and eat. However, a philosopher can only eat spaghetti when they have both left and right forks. Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher. After an individual philosopher finishes eating, they need to put down both forks so that the forks become available to others. A philosopher can take the fork on their right or the one on their left as they become available, but cannot start eating before getting both forks.”

Wikipedia: “In computer science, the dining philosophers problem is an example problem often used in concurrent algorithm design to illustrate synchronization issues and techniques for resolving them. Each philosopher must alternately think and eat. However, a philosopher can only eat spaghetti when they have both left and right forks. Each fork can be held by only one philosopher and so a philosopher can use the fork only if it is not being used by another philosopher. After an individual philosopher finishes eating, they need to put down both forks so that the forks become available to others. A philosopher can take the fork on their right or the one on their left as they become available, but cannot start eating before getting both forks.”

The study of reachability in Petri nets is expansive and a very important thing to consider to fully understand their computational properties. This net is an example of how in some cases, certain computations scale exponentially as new places are added. In this particular net, for each added bit, the path from the tokens going from the top row of places to the bottom, doubles. You can learn more about it in Pawel Sobocinski’s video, which explains open Petri nets.

This net can be thought of as having a producer unit on the left, and a consumer unit on the right, as the title suggests. The consumer unit needs the resources the producer unit creates in order to do its work. An example of this pattern is the producer as a function generating a data object, and the consumer, a function which takes this object as an input and manipulates it in some way.

Expressing events happening in parallel is often necessary. This net shows how a single, sequential process can be split into two branches which run in parallel and then sync. The concept of parallel computing is an important one.

If one imagines that the place on the far left and the place on the far right represent green light, then we, at the least, want to ensure that they are never on at the same time. This net represents such a protocol - a construct in which the undesired state is not possible.