Definition:Unlimited Register Machine/Register/Index

Definition

The subscript (which is a natural number) appended to a URM register is called the index of that register.

Hence, for example, the index of register $R_5$ is $5$.

Also see

• Results about unlimited register machines can be found here.

Sources

• 1963: John C. Shepherdson and H.E. Sturgis: Computability of Recursive Functions (J. ACM Vol. 10, no. 2: pp. 217 – 255)

• 1980: N.J. Cutland: Computability: An Introduction to Recursive Function Theory