16.5 Exercise
A company produces two types of products T1 and T2, which requires the
following resources to produce each unit of the product:
Resource 
T1 
T2 
Labour (hours) 
9 
6 
Pumps (units) 
1 
1 
Tubing (m) 
12 
16 
The amount of profit per unit of products are:

T1
 £350
 T2
 £300
They have the following resources available: 1566 hours of labour, 200
pumps, and 2880 metres of tubing.

Write a program to maximise the profit for the company, using eplex
as a black box solver. Write a predicate that returns the profit and the
values for T1 and T2.
 What program change is required to answer this question:
What profit can be achieved if exactly 150 units of T1 are required?
 What would the profit be if fractional numbers of refrigerators could
be produced?
 Rewrite the program from (1) without optimize/2, using
eplex_solver_setup/1, eplex_solve/1, and eplex_var_get/3.
 In the program from (4), remove the integrality constraints (so that eplex
only sees an LP problem). Solve the integer problem by interleaving
solving of the LP problem with a rounding heuristic:

solve the continuous relaxation
 round the solution for T1 to the nearest integer and instantiate it
Initially just return the maximum profit value.
 resolve the new continuous relaxation
 round the solution for T2 to the nearest integer and instantiate it
 resolve the new continuous relaxation
What is the result in terms of T1, T2 and Profit?
 Rewrite the program from (5) using eplex_solver_setup/4 and automatic
triggering of the solver instead of explicit calls to eplex_solve/1.
The solver should be triggered whenever variables get instantiated.