glanch / BinPacking

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OR_II_BPP_2023

This is a program, which reads an instance of an bpp and solves the bpp with the following BIP model with the SCIP-Framework and soplex as solver.

Modeldefinition BPP

Notation

Indizes und Mengen
$i \in \mathcal{I}$ Items
$j \in \mathcal{J}$ Bins
Parameter
$w_{i}$ Weight of item $i$
$b$ Capacity of a single bin
Entscheidungsvariablen
$X_{ij} \in{0, 1}$ = 1 if we pack item $i$ into bin $j$, 0 otherwise
$Y_{j} \in{0, 1}$ =1 if we use bin $j$, 0 otherwise

Compact model BPP

$$\min \sum_{j \in \mathcal{J}} Y_{j} \\\ s.t. \\\ \sum_{j \in \mathcal{J}} X_{ij} = 1; \forall i \in \mathcal{I} \\\ \sum_{i \in \mathcal{I}} w_{i} \cdot X_{ij} \leq b\cdot Y_{j}; \forall j \in \mathcal{J} \\$$

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