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https://github.com/frankvegadelgado/mids

Siriaisa: Approximate Independent Dominating Set Solver
https://github.com/frankvegadelgado/mids

approximation-algorithms mids np-hard polynomial-algorithm pvsnp

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Siriaisa: Approximate Independent Dominating Set Solver

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# Siriaisa: Approximate Independent Dominating Set Solver

![To my mother who I love.](docs/siriaisa.jpg)

This work builds upon [A 3-Approximation for Independent Dominating Sets: The Siriaisa Algorithm](https://github.com/frankvegadelgado/mids).

---

# Overview of the Minimum Independent Dominating Set (MIDS)

## Definition:

An **independent dominating set** in a graph $G = (V, E)$ is a subset $D \subseteq V$ such that no two vertices in $D$ are adjacent and every vertex not in $D$ is adjacent to at least one vertex in $D$. The **minimum independent dominating set (MIDS)** is the smallest possible independent dominating set in terms of the number of vertices.

## Key Concepts:

1. **Graph Representation**:

- $V$: Set of vertices.
- $E$: Set of edges connecting the vertices.

2. **Independent Dominating Set**:

- A set $D$ where no two vertices in $D$ are adjacent, and for every vertex $v \in V$, either $v \in D$ or $v$ is adjacent to some vertex in $D$.

3. **Minimum Independent Dominating Set**:
- The independent dominating set with the smallest cardinality (i.e., the fewest number of vertices).

## Applications:

- **Network Design**: Ensuring coverage in wireless sensor networks.
- **Social Networks**: Identifying influential nodes.
- **Game Theory**: Strategies in certain types of games.
- **Biology**: Modeling protein-protein interaction networks.

## Computational Complexity:

- **NP-Hard**: Finding the minimum independent dominating set is computationally intensive for large graphs.
- **Approximation Algorithms**: Used to find near-optimal solutions in polynomial time.

## Algorithms:

1. **Greedy Algorithm**:

- Builds a degree-four auxiliary graph, repairs the two lifted vertex seeds into maximal independent sets, and selects the smallest verified candidate.
- Provides the implementation studied in the 3-approximation certificate theorem.

2. **Integer Linear Programming (ILP)**:

- Formulates the problem as an optimization problem.
- Solvable using ILP solvers for exact solutions, though computationally expensive.

3. **Heuristics and Metaheuristics**:
- Genetic algorithms, simulated annealing, etc., for large-scale problems.

## Challenges:

- **Scalability**: Exact algorithms are infeasible for very large graphs.
- **Dynamic Graphs**: Maintaining a minimum independent dominating set in graphs that change over time.

## Research Directions:

- **Parallel Algorithms**: Leveraging multi-core processors and distributed computing.
- **Machine Learning**: Using learning-based approaches to predict dominating sets.
- **Hybrid Methods**: Combining exact and heuristic methods for better performance.

## Conclusion:

The minimum independent dominating set problem is a fundamental issue in graph theory with wide-ranging applications. While it is computationally challenging, various algorithms and heuristics provide practical solutions for different scenarios. Ongoing research continues to improve the efficiency and applicability of these methods.

---

## Problem Statement

Input: A Boolean Adjacency Matrix $M$.

Answer: Find a Minimum Independent Dominating Set.

### Example Instance: 5 x 5 matrix

| | c1 | c2 | c3 | c4 | c5 |
| ------ | --- | --- | --- | --- | --- |
| **r1** | 0 | 0 | 1 | 0 | 1 |
| **r2** | 0 | 0 | 0 | 1 | 0 |
| **r3** | 1 | 0 | 0 | 0 | 1 |
| **r4** | 0 | 1 | 0 | 0 | 0 |
| **r5** | 1 | 0 | 1 | 0 | 0 |

The input for undirected graph is typically provided in [DIMACS](http://dimacs.rutgers.edu/Challenges) format. In this way, the previous adjacency matrix is represented in a text file using the following string representation:

```
p edge 5 4
e 1 3
e 1 5
e 2 4
e 3 5
```

This represents a 5x5 matrix in DIMACS format such that each edge $(v,w)$ appears exactly once in the input file and is not repeated as $(w,v)$. In this format, every edge appears in the form of

```
e W V
```

where the fields W and V specify the endpoints of the edge while the lower-case character `e` signifies that this is an edge descriptor line.

_Example Solution:_

Independent Dominating Set Found `1, 4`: Nodes `1` and `4` constitute an optimal solution.

---

# Compile and Environment

## Prerequisites

- Python >= 3.12

## Installation

```bash
pip install siriaisa
```

## Execution

1. Clone the repository:

```bash
git clone https://github.com/frankvegadelgado/mids.git
cd mids
```

2. Run the script:

```bash
iris -i ./benchmarks/testMatrix1
```

utilizing the `iris` command provided by Siriaisa's library to execute the Boolean adjacency matrix `mids\benchmarks\testMatrix1`. The file `testMatrix1` represents the example described herein. We also support `.xz`, `.lzma`, `.bz2`, and `.bzip2` compressed text files.

**Example Output:**

```
testMatrix1: Independent Dominating Set Found 1, 4
```

This indicates nodes `1, 4` form an Independent Dominating Set.

---

## Independent Dominating Set Size

Use the `-c` flag to count the nodes in the Independent Dominating Set:

```bash
iris -i ./benchmarks/testMatrix2 -c
```

**Output:**

```
testMatrix2: Independent Dominating Set Size 2
```

---

# Command Options

Display help and options:

```bash
iris -h
```

**Output:**

```bash
usage: iris [-h] -i INPUTFILE [-a] [-b] [-c] [-v] [-l] [--version]

Solve the Approximate Independent Dominating Set for undirected graph encoded in DIMACS format.

options:
-h, --help show this help message and exit
-i INPUTFILE, --inputFile INPUTFILE
input file path
-a, --approximation enable comparison with a polynomial-time approximation approach within a maximum degree factor
-b, --bruteForce enable comparison with the exponential-time brute-force approach
-c, --count calculate the size of the Independent Dominating Set
-v, --verbose enable verbose output
-l, --log enable file logging
--version show program's version number and exit
```

---

# Batch Execution

Batch execution allows you to solve multiple graphs within a directory consecutively.

To view available command-line options for the `batch_iris` command, use the following in your terminal or command prompt:

```bash
batch_iris -h
```

This will display the following help information:

```bash
usage: batch_iris [-h] -i INPUTDIRECTORY [-a] [-b] [-c] [-v] [-l] [--version]

Solve the Approximate Independent Dominating Set for all undirected graphs encoded in DIMACS format and stored in a directory.

options:
-h, --help show this help message and exit
-i INPUTDIRECTORY, --inputDirectory INPUTDIRECTORY
Input directory path
-a, --approximation enable comparison with a polynomial-time approximation approach within a maximum degree factor
-b, --bruteForce enable comparison with the exponential-time brute-force approach
-c, --count calculate the size of the Independent Dominating Set
-v, --verbose enable verbose output
-l, --log enable file logging
--version show program's version number and exit
```

---

# Testing Application

A command-line utility named `test_iris` is provided for evaluating the Algorithm using randomly generated, large sparse matrices. It supports the following options:

```bash
usage: test_iris [-h] -d DIMENSION [-n NUM_TESTS] [-s SPARSITY] [-a] [-b] [-c] [-w] [-v] [-l] [--version]

The Siriaisa Testing Application using randomly generated, large sparse matrices.

options:
-h, --help show this help message and exit
-d DIMENSION, --dimension DIMENSION
an integer specifying the dimensions of the square matrices
-n NUM_TESTS, --num_tests NUM_TESTS
an integer specifying the number of tests to run
-s SPARSITY, --sparsity SPARSITY
sparsity of the matrices (0.0 for dense, close to 1.0 for very sparse)
-a, --approximation enable comparison with a polynomial-time approximation approach within a maximum degree factor
-b, --bruteForce enable comparison with the exponential-time brute-force approach
-c, --count calculate the size of the Independent Dominating Set
-w, --write write the generated random matrix to a file in the current directory
-v, --verbose enable verbose output
-l, --log enable file logging
--version show program's version number and exit
```

---

# Code

- Python implementation by **Frank Vega**.

---

# Complexity

```diff
+ Siriaisa separates feasibility from the approximation certificate: every returned set is verified as independent and dominating, while a universal proof of the 3-approximation certificate would imply P = NP by known MIDS inapproximability results.
```

---

# License

- MIT License.