Although encouragement is valuable in investigation of unusual case, but it is still necessary to discuss the following questions: in which circumstance policemen can carry out encouragement, and in which circumstance their encouragement is misuse of authority.
The fourth chapter of the paper discusser the control and prevention measures of the underworld-type organizations from the angle of crime prevention, based on the actual conditions, the paper has put forth the countermeasures for controlling and fighting against crimes by such kinds of underworld-type organizations according to the aspects such as social control, litigation and legislation, anti-corruption , reconnaissance of crime case involving underworld-type organizations.
This system can also make use of the electronics map labeling, generate the subject map, show various information by multi-media, and provide the most straightforward clues to police officials to analyze the case circumstance.
In the present paper we study the remaing nontrivial case, that of a negative central charge-N.
The method applies to the standard arithmetic subgroups ofSO(n,1) (a case which was proved previously by Millson [Mi]), to the non-arithmetic lattices inSO(n,1) constructed by Gromov and Piatetski-Shapiro [GPS] and to groups generated by reflections.
In the case of 4-dimensional anticommutative algebras a construction is given that links the associated cubic surface and the 27 lines on it with the structure of subalgebras of the algebra.
In the case of 3-dimensional commutative algebras a new proof of a recent theorem of Katsylo and Mikhailov about the 28 bitangents to the associated plane quartic is given.
As in the case of Mumford's geometric invariant theory (which concerns projective good quotients) the problem can be reduced to the case of an action of a torus.