A Decomposition Theorem for Cayley Graphs of Picard Group Quotients
نویسنده
چکیده
The Picard group is defined as Γ = SL(2,Z[i]); the ring of 2× 2 matrices with Gaussian integer entries and determinant one. We consider certain graphs associated to quotients Γ/Γ(p) where p is a prime congruent to three mod four and Γ(p) is the congruence subgroup of level p. We prove a decomposition theorem on the vertices of these graphs, and use this decomposition to derive upper and lower bounds on their isoperimetric numbers.
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