How to find the maximum matching in a network?

To find the maximum matching in a network, we can use the augmenting path algorithm.

The augmenting path algorithm is a method used to find the maximum matching in a network. It involves finding a path in the network that starts and ends with unmatched vertices, and alternates between matched and unmatched edges. This path is then used to augment the current matching by flipping the status of the edges along the path.

The algorithm starts with an empty matching and repeatedly searches for augmenting paths until no more can be found. To search for an augmenting path, we can use a depth-first search or a breadth-first search. Once an augmenting path is found, we can flip the status of the edges along the path to obtain a new matching. This process is repeated until no more augmenting paths can be found.

To illustrate the algorithm, consider the following network:

```
A -- B
| |
C -- D
```

Suppose we want to find the maximum matching. We can start with an empty matching and search for augmenting paths. One possible augmenting path is A-C-D-B, which alternates between matched and unmatched edges. Flipping the status of the edges along this path gives us a new matching:

```
A -- B
| |
C D
```

We can then search for more augmenting paths and repeat the process until no more can be found. In this case, there are no more augmenting paths, so the maximum matching is:

```
A B
| |
C D
```

In summary, the augmenting path algorithm is a powerful method for finding the maximum matching in a network. It involves searching for augmenting paths and flipping the status of the edges along the path to obtain a new matching. The algorithm can be implemented using a depth-first search or a breadth-first search.