NLP: How to group sub-field into fields? Suppose I have a list of strings that captures a sub-field of academic research and would like to group them as higher-level fields.
For example, 

'Quantum Mechanics'  =&gt; 'Physics'
'Abstract Algebra'   =&gt; 'Mathematics'
....


My understanding is that standard NLP techniques may not fit here, because the relationship between sub-fields and fields are linked by its meanings but not word-frequency or word-embedding etc. 

I wonder if there is anything done that could be useful to tackle this problem (papers or packages)?
You need an ontology or any form of third-party data which describes the relationships between fields and sub-fields. You could use resources such as Wikipedia categories or standard library classifications for instance. There are probably other options for scientific fields.