  The main purpose of this paper is to formalize the modelling process,
analysis and mathematical definition of corruption when entering into a
contract between principal agent and producers. The formulation of the problem
and the definition of concepts for the general case are considered. For
definiteness, all calculations and formulas are given for the case of three
producers, one principal agent and one intermediary. Economic analysis of
corruption allowed building a mathematical model of interaction between agents.
Financial resources distribution problem in a contract with a corrupted
intermediary is considered.Then proposed conditions for corruption emergence
and its possible consequences. Optimal non-corruption schemes of financial
resources distribution in a contract are formed, when principal agent's choice
is limited first only by asymmetrical information and then also by external
influences.Numerical examples suggesting optimal corruption-free agents'
behaviour are presented.
