| Description: Define the class of
converse reflexive relations. This is practically
dfcnvrefrels2 39207 (which uses the traditional subclass
relation ⊆) :
we use converse subset relation (brcnvssr 39185) here to ensure the
comparability to the definitions of the classes of all reflexive
(df-ref 23645), symmetric (df-syms 39221) and transitive (df-trs 39255) sets.
We use this concept to define functions (df-funsALTV 39365, df-funALTV 39366)
and disjoints (df-disjs 39388, df-disjALTV 39389).
For sets, being an element of the class of converse reflexive relations is
equivalent to satisfying the converse reflexive relation predicate, see
elcnvrefrelsrel 39215. Alternate definitions are dfcnvrefrels2 39207 and
dfcnvrefrels3 39208. (Contributed by Peter Mazsa,
7-Jul-2019.) |
