I am trying to reduce a boolean expression with a K-map. But when I make the map I end up with three true values which is not possible to make a map with.

Is there a way to simplify this map?

The original expression was:

```
Y1 = A1 B1 A2' B2' + A1 B1 A2 B2' + A1 B1 A2' B2

```

Thanks a lot for the help. The picture shows the truth tables and the k-map

[![enter image description here](https://i.stack.imgur.com/Hsdty.png)](https://i.stack.imgur.com/Hsdty.png)