## Supports of doubly stochastic measures.(English)Zbl 0844.60002

Summary: Recent work has shown that extreme doubly stochastic measures are supported on sets that have no axial cycles. We give a new proof of this result and examine the supporting set structure more closely. It is shown that the property of no axial cycles leads to a tree like structure which naturally partitions the support into a collection of disjoint graphs of functions from the $$x$$-axis to the $$y$$-axis and from the $$y$$-axis to the $$x$$-axis. These functions are called a limb numbering system. It is shown that if the disjoint graphs in the limb numbering system are measurable, then the supporting set supports a unique doubly stochastic measure. Further, the limb structure can be used to develop a general method for constructing sets which support a unique doubly stochastic measure.

### MSC:

 60A10 Probabilistic measure theory
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