Harmonic Differential Operators.
A partition of the Catalan numbers and enumeration of genealogical trees
A special relational structure, called genealogical tree, is introduced; its social interpretation and geometrical realizations are discussed. The numbers of all abstract genealogical trees with exactly n+1 nodes and k leaves is found by means of enumeration of code words. For each n, the form a partition of the n-th Catalan numer Cₙ, that means .
Lorentzian geometry as determined by the volumes of small truncated light cones
On constant solutions of the Yang-Mills equations
A formal series solution of the one-dimensional Schrödinger equation
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