Pascal’s Hexagram and Desargues Configurations

This paper solves an enumerative problem which arises naturally in the context of Pascal’s hexagram. We prove that a general Desargues configuration in the plane is associated to six conical sextuples via the theorems of Pascal and Kirkman. Moreover, the Galois group associated to this problem is isomorphic to the symmetric group on six letters.

Non-crystallographic symmetry of liquid metal, flat crystallographic faults and polymorph transformation of the M7C3carbide

The fine lamellar fault structure of primary M7C3carbide particles in the heat-resistant Fe–Cr–Ni–C alloy of the HP series (0.45C–25Cr–35Ni) in the cast condition has been revealed using transmission electron microscopy. The lamellar fault structure is regarded as an inheritance of the initial melt structure. A one-to-one correspondence between the crystal structures of M7C3, M5C2, M3C and M23C6carbides and constructions of the projective 103Desargues configuration and its subconfigurations is shown. Mutual mapping between 103Desargues subconfigurations determines transformations of the ten-vertex equal-edged triangulated clusters appearing as building units of these carbides.

FEATURES OF COMPUTER IMPLEMENTATION OF CONSTRUCTING PLANAR DESARGUES CONFIGURATION

The authors present the main properties of the planar configuration of Desargues, which open the possibility of its widespread use in architectural design and the design of complex volumes, consisting of a series of simple overlapping forms. However, the computer implementation of Desargues configuration construction is associated with certain difficulties caused by the fact that the monitor can only discretely represent the graphical information. In this article we identified and analyzed the properties of Desargues configuration, the use of which allows overcoming these difficulties and solving the problem of the limited capacity of monitors in the development of complex architectural forms with the help of computer graphics. Along with this, the use of the allocated properties allows predicting complex effects of the perception of architectural forms, for example, the difference of perception of architectural objects near and afar with account for perspective distortion, and they are also the basis for the development of the algorithm of construction sequence during design.

Fundamental group of Desargues configuration spaces

We compute the fundamental group of various spaces of Desargues configurations in complex projective spaces: planar and non-planar configurations, with a fixed center and also with an arbitrary center.

Pseudo-Homogeneous Coordinates for Hughes Planes

Among the projective planes, the class of Hughes planes has received much interest, for several good reasons. However, the existing descriptions of these planes are somewhat unsatisfactory. We introduce pseudo-homogeneous coordinates which at the same time are easy to handle and give insight into the action of the group that is generated by all elations of the desarguesian Baer subplane of a Hughes plane. The information about the orbit decomposition is then used to give a description in terms of coset spaces of this group. Finally, we exhibit a non-closing Desargues configuration in terms of coordinates.