Graphs and thermodynamics

Graphs are used in many fields of chemistry for codification and model purposes. One of these fields is widely known under the acronym QSAR/QSPR, i.e., quantitative structure–activity/structure–property relationships. In chemical graph studies directed graphs, known as digraphs, i.e., graphs with a preferred direction, have mainly been used to codify chemical reaction networks. Actually, digraphs, especially directed acyclic graphs together with simple graphs, can be used to draw a metalanguage of thermodynamics that codifies rules and properties which can be used to automatically derive many well-known, and less-known, thermodynamic relationships.