Understanding mutual relation between informal meaning in human mind and formalised semantics is crucial for formalizing human processes of thinking when performing them on computers. It is fictious to suppose machines are able to process informal meaning in the way as it is in human mind. On the other side, reflecting the requirements for rapid, flexible and automated changes in real world a new quality of informal processing with help of machines is needed. That is why binding an informal meaning and formal semantics is in the centre of many applications that have attributes of machine intelligence. Moreover, we are strongly interested in automating the production of these applications. By other words, we need rather to evolve them in an automated manner than to construct them mannually. This paper is devoted to mutual binding of metasemantics via semantics to informal meaning, with abstract interpretation as a central point, introducing simple example, how it works. We define mutual binding of informal meaning to abstract symbols of regular expression. We define the semantics of operations in terms of metaoperations inherited from EBNF metalevel, and finally, we derive the minimum-state deterministic finite state automaton, which reflects active bindings to informal meaning in its states.