The exploration of pathways and alternative pathways that have a specific function is of interest in numerous chemical contexts. A framework for specifying and searching for pathways has previously been developed, but a focus on which of the many pathway solutions are realisable, or can be made realisable, is missing. Realisable here means that there actually exists some sequencing of the reactions of the pathway that will execute the pathway. We present a method for analysing the realisability of pathways based on the reachability question in Petri nets. For realisable pathways, our method also provides a certificate encoding an order of the reactions which realises the pathway. We present two extended notions of realisability of pathways, one of which is related to the concept of network catalysts. We exemplify our findings on the pentose phosphate pathway. Furthermore, we discuss the relevance of our concepts for elucidating the choices often implicitly made when depicting pathways. Lastly, we lay the foundation for the mathematical theory of realisability.

翻译：在众多化学背景下，探索具有特定功能的通路及替代通路具有重要意义。此前已开发出用于指定和搜索通路的框架，但尚未关注众多通路解中哪些是可实现的或可被实现化的。此处“可实现”意指实际存在某种反应序列能够执行该通路。我们提出一种基于Petri网可达性问题的通路可实现性分析方法。对于可实现通路，该方法还能提供实现该通路的反应顺序编码凭证。我们提出两种扩展的通路可实现性概念，其中一种与网络催化剂概念相关。我们以磷酸戊糖途径为例验证了研究结果。此外，我们讨论了所提概念对于阐明通路图示中常隐含选择的重要意义。最后，我们为可实现性的数学理论奠定了基础。