Definition:Reflexive Reduction

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Let $\mathcal R$ be a relation on a set $S$.

The reflexive reduction of $\mathcal R$ is denoted $\mathcal R^\ne$, and is defined as:

$\mathcal R^\ne := \mathcal R \setminus \left\{{\left({x, x}\right): x \in S}\right\}$

Also see

From Set Difference as Intersection with Relative Complement and Intersection is Largest Subset, it follows that $\mathcal R^\ne$ is the largest antireflexive relation on $S$ which is contained in $\mathcal R$.

Thus if $\mathcal R$ is antireflexive, then $\mathcal R = \mathcal R^\ne$.

  • Results about reflexive reductions can be found here.