Add recnprss to iset.mm

Copied without change from set.mm.

Author: jkingdon

iset.mm

@@ -136601,6 +136601,12 @@ S C_ ( P ( ball ` D ) T ) ) $=
       POZQUFR $.
   $}
 
+  $( Both ` RR ` and ` CC ` are subsets of ` CC ` .  (Contributed by Mario
+     Carneiro, 10-Feb-2015.) $)
+  recnprss $p |- ( S e. { RR , CC } -> S C_ CC ) $=
+    ( cr cc cpr wcel wceq wo wss elpri ax-resscn sseq1 mpbiri eqimss jaoi syl )
+    ABCDEABFZACFZGACHZABCIPRQPRBCHJABCKLACMNO $.
+
 
 $(
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