  We postulates, and then show experimentally, that liquidity deficit is the
driving force of the markets. In the first part of the paper a kinematic of
liquidity deficit is developed. The calculus-like approach, which is based on
Radon--Nikodym derivatives and their generalization, allows us to calculate
important characteristics of observable market dynamics. In the second part of
the paper this calculus is used in an attempt to build a dynamic equation in
the form: future price tend to the value maximizing the number of shares traded
per unit time. To build a practical automated trading machine P&L dynamics
instead of price dynamics is considered. This allows a trading automate
resilient to catastrophic P&L drains to be built. The results are very
promising, yet when all the fees and trading commissions are taken into
account, are close to breakeven. In the end of the paper important criteria for
automated trading systems are presented. We list the system types that can and
cannot make money on the market. These criteria can be successfully applied not
only by automated trading machines, but also by a human trader.
