Abstract Background This article coincides with the 40 year anniversary of the first published works devoted to the creation of algorithms for computer-aided structure elucidation (CASE). The general principles on which CASE methods are based will be reviewed and the present state of the art in this field will be described using. as an example. the expert system Structure Elucidator. https://www.marcelovicente.com/product-category/hair-defining-spray/