let N be e_net; :: thesis: ( ( the entrance of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] & ( the escape of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] )

( the entrance of N \ (id the carrier of N) c= [:(e_Transitions N),(e_Places N):] & the escape of N \ (id the carrier of N) c= [:(e_Transitions N),(e_Places N):] ) by Th18;

hence ( ( the entrance of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] & ( the escape of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] ) by SYSREL:4; :: thesis: verum

( the entrance of N \ (id the carrier of N) c= [:(e_Transitions N),(e_Places N):] & the escape of N \ (id the carrier of N) c= [:(e_Transitions N),(e_Places N):] ) by Th18;

hence ( ( the entrance of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] & ( the escape of N \ (id the carrier of N)) ~ c= [:(e_Places N),(e_Transitions N):] ) by SYSREL:4; :: thesis: verum