Spreads of right quadratic skew field extensions
Author(s) -
Hans Havlicek
Publication year - 1994
Publication title -
geometriae dedicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.746
H-Index - 43
eISSN - 1572-9168
pISSN - 0046-5755
DOI - 10.1007/bf01610624
Subject(s) - mathematics , skew , quadratic equation , projective space , projective geometry , pure mathematics , field (mathematics) , isomorphism (crystallography) , projective plane , invariant (physics) , discrete mathematics , combinatorics , differential geometry , geometry , projective test , computer science , crystal structure , chemistry , correlation , crystallography , telecommunications , mathematical physics
LetL/K be a right quadratic (skew) field extension and let be a 3-dimensional projective space overK which is embedded in a 3-dimensional projective space overL. Moreover, let I be a line of which carries no point of. The main result is that — even whenL orK is a skew field — the following holds true: A Desarguesian spread of is given by the set of all lines of which are indicated by the points of I. A spread of arises in this way if, and only if, there exists an isomorphism ofL onto the kernel of the spread such thatK is elementwise invariant. Furthermore, a geometric characterization of right quadratic extensions with a left degree other than 2 and of quadratic Galois extensions is given.
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