# More Groupokus ([home](https://github.com/alexhkurz/introduction-to-numbers/blob/master/README.md) ... [previous](https://hackmd.io/@alexhkurz/B1w9oSPiL) ... [next](https://hackmd.io/@alexhkurz/S17OoT2oI)) Recall the rules of [Groupoku](https://hackmd.io/@alexhkurz/B1w9oSPiL): - Every row and column needs to contain every number exactly once (unique solution to equations $ax=b$). - The top-left down-right diagonal gives a mirror symmetry (commutativity). - At the end we need to check for associativity using the program [groupoku](https://github.com/alexhkurz/introduction-to-numbers/blob/master/src/groupoku.py). **Groupoku:** Show that there is one and only one solution to |0| 1| 2| 3| |:---:|:---:|:---:|:---:|:---:| | 1 |3|| | 2|||| | 3|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3| |:---:|:---:|:---:|:---:|:---:| | 1 |0|| | 2||0|| | 3|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3| |:---:|:---:|:---:|:---:|:---:| | 1 |0|| | 2||1|| | 3|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|2|| | 2||3|| | 3|||| | 4|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|2|| | 2||4|| | 3|||| | 4|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|3|| | 2||1|| | 3|||| | 4|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|3|| | 2||4|| | 3|||| | 4|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|4|| | 2||1|| | 3|||| | 4|||| **Groupoku:** Show that there is exactly one solution to |0| 1| 2| 3|4 |:---:|:---:|:---:|:---:|:---:| | 1|4|| | 2||3|| | 3|||| | 4||||