d (source code)
= d
{scope}
For a <binary relation> $R\subseteq A\times A$, <reflexivity> means $aRa$ for every $a\in A$; a <symmetric relation> satisfies $aRb\Rightarrow bRa$ for every $a,b\in A$; an <antisymmetric relation> satisfies $(aRb\text{ and }bRa)\Rightarrow a=b$ for every $a,b\in A$; <transitivity> means $(aRb\text{ and }bRc)\Rightarrow aRc$ for every $a,b,c\in A$; an <irreflexive relation> satisfies $\neg(aRa)$ for every $a\in A$. In particular, failure of <reflexivity> means at least one missing diagonal pair, whereas <irreflexivity> requires every diagonal pair to be missing.
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