Integer Programming

ivan gabrovski

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About this app

Android application (Java) for solving integer and mixed-integer linear problems.

## Opportunities
- Model text editor (LP format): `max:` / `min:`, constraints with `<=`, `>=`, `=`, intervals `2 <= x + y <= 8`, labels, fractions `3/4 x`, comments `#`.
- Variables are integers and ≥ 0 by default; `bin a, b` – binary, `cont z` – continuous.
- **Exact arithmetic** with fractions (BigInteger) – two-phase simplex with Bland's rule.
- **Branch & Bound** (depth-first search, branching on the most fractional variable, truncation on the boundary).
- **Gomori's truncation planes** – each truncation is displayed in the output variables; in case of slow convergence, B&B finishes on the boosted model (the answer remains correct).
- Results: optimal solution, LP relaxation, integer gap, statistics.
- **Graph** for models with 2 variables: feasible region, integer points, intercepts, direction of the objective function, the two optima.
- **Branch & Bound Tree**, drawn graphically + text log of nodes.
- 16 sample tasks (8 from practice: bakery, bar cutting, staff scheduling, trucks, investment projects, setup costs, warehouse selection, container packing + 8 training ones), history in SQLite, report sharing.
- Languages ​​in the application (regardless of the device language): English (default), Bulgarian, Deutsch, Français, Español.
- Light and dark theme.