Bridges of Markov counting processes. Reciprocal classes and duality   formulas
  Processes having the same bridges are said to belong to the same reciprocal class. In this article we analyze reciprocal classes of Markov counting processes by identifying their reciprocal invariants and we characterize them as the set of counting processes satisfying some duality formula. 
Giovanni Conforti, Christian L\'eonard (MODAL'X), R\"udiger Murr,   Sylvie Roelly
math.PR