The Nobel Prize was established according to Nobel's will. In his will, Nobel said:
Here, I ask the executor to dispose of the remaining property I can realize in the following ways: convert the above property into cash, and then make safe and reliable investment; Use this fund to establish a foundation, and the interest generated by the fund will be awarded annually to those who have made outstanding contributions to mankind in the previous year. Divide the interest into five equal parts as follows:
A prize is awarded to the person who has made the most important discovery or invention in physics;
One prize is awarded to the person who has made the most important discovery or improvement in chemistry;
A prize is awarded to those who have made the most important discoveries in the fields of medicine and physiology;
An award is awarded to those who have created the best works with ideal tendency in the literary world;
The last prize is awarded to those who have done their best or made the greatest contribution to promoting national unity and friendship, abolishing or reducing the standing army, and organizing and publicizing the peace conference.
There is no Nobel Prize for Mathematics because there is no mention of setting up a prize for mathematics in Nobel's will.