Workflow Patterns
You find the Workflow Patterns at
http://workflowpatterns.com.
a) Represent a
Multi-Choice (OR-Split) by only using the patterns
Exclusive Choice (XOR-Split),
Simple Merge (XOR-Join) and
Parallel Split (AND-Split). The
Multi-Choice should have three succeeding activities.
b) Represent a
2-out-of-3 Join by only using the patterns
Discriminator,
AND-Split and
AND-Join.
Hint: You could use BPMN to visualize your result.
More information on the Workflow Patterns can be found in the book in chapter 4.1.