Idempotent factorizations of singular 2 × 2 matrices over quadratic integer rings
Idempotent factorizations of singular 2 × 2 matrices over quadratic integer rings
Let D be the ring of integers of a quadratic number field Q[d]. We study the factorizations of 2×2 matrices over D into idempotent factors. When d<0 there exist singular matrices that do not admit idempotent factorizations, due to results by Cohn and by the authors Cozzu and Zanardo. We …