Uploaded example 39 from the manual

Example39_Merging_Root_Events_to_Reduce_Run_Time.mp

+/* Example39_Merging_Root_Events_to_Reduce_Run_Time.mp
+
+	Complex MP models may have large number of root events with several
+coordination operations performed on clusters of roots. This may be
+system’s architecture model with a large number of actors (components)
+and interactions (connectors) between them. Usually coordination operations
+will be placed in schema’s body following the corresponding root event
+descriptions and performed during the derivation as described in Section
+3. Derivation for such “heavy” MP models in Firebird may take too much
+time even for scope 1. Fortunately, the “layered derivation” strategy
+implemented in MP may help to speed up the trace derivation, and in
+many cases makes it possible to work with a pretty large and complex
+MP models. The idea is simple – organize the derivation as a hierarchy
+of smaller derivations.
+
+	Here is an example of how to benefit from the “layered derivation”.
+Schema S1 has several interacting root events, where roots B and C have
+several coordination operations between them. These coordination operations
+will be performed repeatedly each time when derivation process backtracks
+and performs new top-down pass through schema’s code for the next trace
+derivation.
+
+	B and C have two coordination operations between them: COORDINATE
+and SHARE ALL. To delegate this “heavy” coordination to a separate
+derivation task we introduce a separate root event B_and_C to
+encapsulate the trace segment derivation (including the coordination)
+for B and C.
+
+*/
+SCHEMA Merging_Root_Events_to_Reduce_Run_Time
+ROOT A: (* ( work | send_to_B) *);
+ROOT B: (*<1.. $$scope + 1>
+( work | receive_from_A | send_to_C ) *);
+COORDINATE $a: send_to_B,
+$b: receive_from_A
+DO ADD $a PRECEDES $b; OD;
+ROOT C: (*<1.. $$scope + 1>
+( work | receive_from_B | send_to_D ) *);
+COORDINATE $a: send_to_C,
+$b: receive_from_B
+DO ADD $a PRECEDES $b; OD;
+B, C SHARE ALL work;
+ROOT D: (* (work | receive_from_C ) *);
+COORDINATE $a: send_to_D,
+$b: receive_from_C
+DO ADD $a PRECEDES $b; OD;