Pensieve Header: Is β calculus related to twisted Drinfel’d doubles?

SetDirectory["C:\\drorbn\\AcademicPensieve\\2012-01"];
<< betaCalculus.m

(a ar[1,1])**(b ar[1,1])

((a ar[1,1])**(b ar[1,1]))**(c ar[1,1])

(a ar[1,1])**((b ar[1,1])**(c ar[1,1]))