Allocation Optimization
1. **Stating the problem:**
We want to allocate the number of groups $L$, $C$, and $P$ (lectures, classes, practicals) to maximize appreciation while not exceeding a budget of 95 million.
2. **Formulating the integer linear programming (ILP) problem:**
Let:
- $L$ = number of lecture groups
- $C$ = number of class groups
- $P$ = number of practical groups
Given:
- Cost per unit: $20, 25, 50$ million for $L, C, P$ respectively
- Appreciation per unit: $1, 2, 4$ for $L, C, P$ respectively
- Budget constraint: $20L + 25C + 50P \leq 95$
Objective: maximize total appreciation
$$ \max_{L, C, P \in \mathbb{Z}_{\geq 0}} \, Z = 1 \cdot L + 2 \cdot C + 4 \cdot P $$
Subject to:
$$ 20L + 25C + 50P \leq 95 $$
$$ L, C, P \geq 0 \, \text{and integers} $$
3. **Drawing a convenient network (conceptual):**
- We can see the problem as stages of decision making in dynamic programming, where each stage corresponds to one work form.
- Stage 1: Decide $L$ (lectures), possible values given budget constraints
- Stage 2: Decide $C$ (classes) given remaining budget
- Stage 3: Decide $P$ (practicals) given remaining budget
Each transition consumes part of the budget and adds appreciation.
4. **Solving using dynamic programming:**
Define the value function $V_i(b)$ as the maximum appreciation achievable from stage $i$ onward with budget $b$ remaining.
- Stage 3 (practicals):
$$ V_3(b) = \max_{0 \leq p \leq \lfloor b/50 \rfloor} 4p $$
- Stage 2 (classes):
$$ V_2(b) = \max_{0 \leq c \leq \lfloor b/25 \rfloor} \left[ 2c + V_3(b - 25c) \right] $$
- Stage 1 (lectures):
$$ V_1(b) = \max_{0 \leq l \leq \lfloor b/20 \rfloor} \left[ l + V_2(b - 20l) \right] $$
With initial budget $b=95$, the solution is:
$$ Z^* = V_1(95) $$
5. **General Bellman equation for this problem:**
For stage $i = 1,2,3$ with decision variable $x_i$ costing $c_i$ per unit and appreciation $a_i$ per unit, and budget $b$ remaining,
$$
V_i(b) = \max_{0 \leq x_i \leq \lfloor b/c_i \rfloor} \left[ a_i x_i + V_{i+1}(b - c_i x_i) \right]
$$
with terminal condition:
$$ V_{4}(b) = 0 $$
because after the last stage there is no further appreciation.
**Final answer:**
The ILP formulation is:
$$\max_{L,C,P \in \mathbb{Z}_{\geq 0}} L + 2C + 4P$$
subject to
$$20L + 25C + 50P \leq 95$$
and using dynamic programming as above optimizes the allocation maximizing appreciation without exceeding the budget.