algebraic cone; monoid action; group action; orbit; action with unique fixed point; algebra automorphism; stable ideal; irreducible algebraic variety Drinfeld modules; elliptic sheaves; elliptic modules; level structure; central simple algebra; moduli spaces; reciprocity law; local Langlands conjecture; Selberg trace formula; Grothendieck-Lefschetz fixed point formula; Tate conjectures 