ExtensionsBy adding some functionality to the existing petrinet, several extensions can be formulated that perform extended functions. There are two main types of Petri net extensions. Types of extensions 1) fully backwards compatible The backward compatibility of a petrinet is decided based on whether or not the original Petri net can be restored after the extension. These petrinets are usually extended via a mathematical formula and can therefore be reversed. Colored Petrinets are examples of backward-compatible Petrinets. If the properties can be modeled in the original petrinet, they are not real extensions.2) Not backwards compatibleThese are the petrinets whose extensions cannot be reverted to recover the original petrinet. For example, timed petrinets cannot be reversed from their extended versions since they are a function of time. Backward-compatible extensions are sometimes very powerful, but do not possess the full range of mathematical tools available for the analysis of ordinary Petri nets. Types of important extended petrinets 1) Additional types of archisa) Reset arcThis type of arc it never imposes any preconditions for firing. It also empties the space when the transition starts, thus making it difficult or impossible to decide reachability. However, in the recovery arc, properties such as termination are decidable.b) Inhibitory arcThis type of arc imposes a precondition that allows the transition to be triggered only when the space is empty. Furthermore, it allows arbitrary calculations on the number of tokens. 2) Colored Petrinets Unlike the indistinguishable feature of tokens in standard petrinets, each token carries a value in a colored Petri net. The CPN instruments are......in the center of the sheet......continuedFig. Example of a marked graph3) Free choiceHere, an arc from a location to a transition can be the only arc from that location or the only arc to that transition. Competition and conflict can exist, but not at the same time. 4) Extended free choice These Petri nets are a super set of free choice that can be transformed into free choice. 5) Asymmetric Choice Network In case of asymmetric choice network, "confusion", or competition and conflict may occur, but will not occur symmetrically. Mathematically, it can be represented as follows: Extensions and restrictions are also possible and are applied to Petri nets. We obtain the restricted Petrinet by suppressing some features of ordinary Petri nets. In normal Petri nets, all weights are oneWorks Citedhttp://embedded.eecs.berkeley.edu/Respep/Research/hsc/class.F03/ee249/discussionpapers/PetriNets.pdf