\vartriangleleftThe symbol \vartriangleleft is used to denote a relation that is often interpreted as 'is a left normal subgroup of' in group theory. It can also be used in other contexts to represent a relation where one element is related to another in a specific way, depending on the defined context.
H is a normal subgroup of G in group theory.
H \vartriangleleft GA is related to B by the \vartriangleleft relation, context-specific.
A \vartriangleleft Bx is related to y by the \vartriangleleft relation, context-specific.
x \vartriangleleft y