10.9 The code repository contains a logical reasoning system whose components can be replaced by other versions. Re-implement some or all of the following components, and make sure that the resulting system works using the circuit example from Chapter 8.

a. Basic data types and access functions for sentences and their components.

b. STORE and FETCH for atomic sentences (disregarding efficiency).

c. Efficient indexing mechanisms for STORE and FETCH.

d. A unification algorithm.

e. A forward-chaining algorithm.

f. A backward-chaining algorithm using iterative deepening.