Rizza manifold

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In differential geometry a Rizza manifold, named after Giovanni Battista Rizza, [1] is an almost complex manifold also supporting a Finsler structure: this kind of manifold is also referred as almost Hermitian Finsler manifold. [2]

Contents

History

The history of Rizza manifolds follows the history of the structure that such objects carry. According to ShoshichiKobayashi  ( 1975 ), the geometry of complex Finsler structures was first studied in Rizza's 1964 paper "F-forme quadratiche ed hermitiane", but Rizza announced his results nearly two years before, in the short communications ( Rizza 1962a ) and ( Rizza 1962b ), proving them in the article ( Rizza 1963 ), nearly one year earlier than the one cited by Kobayashi. Rizza called this differential geometric structure, defined on even-dimensional manifolds, "Struttura di Finsler quasi Hermitiana": [3] his motivation for the introduction of the concept seems to be the aim of comparing two different structures existing on the same manifold. [4] Later Ichijyō (1988 , p. 1) started calling this structure "Rizza structure", and manifolds carrying it "Rizza manifolds". [1]

Formal definition

The content of this paragraph closely follows references ( Rizza 1963 ) and ( Ichijyō 1988 ), borrowing the scheme of notation equally from both sources. Precisely, given a differentiable manifold M and one of its points xM

Definition 1. Let M be a 2n-dimensional Finsler manifold, n ≥ 1, and let F : TM → ℝ its Finsler function. If the condition

(1)     

holds true, then M is a Rizza Manifold.

See also

Notes

  1. 1 2 The dedication of the work ( Ichijyō 1988 , p. 1) reads:-"Dedicated to professor G. B. Rizza, who is the originator of the notion of Rizza manifolds."
  2. See ( Ichijyō 1988 , p. 6).
  3. "Almost Hermitian Finsler structure": see ( Rizza 1962b , pp. 271, 273–274) and ( Rizza 1963 , pp. 83, 90–91).
  4. Rizza (1962b , p. 1) himself states:-"L'esistenza di strutture di tipo diverso su una medesima varietà dà sempre luogo a problemi di confronto (The existence of structures of different kind on the same manifold always gives rise to comparison problems)".

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