Examples of inappropriate credit in mathematics

Question

What are some known cases of inappropriate credit in mathematics?

Here, "inappropriate credit" means a common attribution that is not totally fair because someone who also discovered the result is forgotten or because the one who is named did not discover the result. For example:

• From the chronological point of view, the Argand diagram should be called Wessel diagram.
• From the discovery point of view, the L'Hospital's rule should be called Bernoulli's rule.

The answer can address any field (this is why I added some specific tags).

Answer 1

An interesting inappropriate credit is for the Diffie-Hellman key exchange, not mentioning Ralph Merkle.

Hellman himself suggested the algorithm be called Diffie–Hellman–Merkle key exchange and has quoted that:

"The system...has since become known as Diffie–Hellman key exchange. While that system was first described in a paper by Diffie and me, it is a public key distribution system, a concept developed by Merkle, and hence should be called 'Diffie–Hellman–Merkle key exchange' if names are to be associated with it. I hope this small pulpit might help in that endeavor to recognize Merkle's equal contribution to the invention of public key cryptography."

I find it very interesting that one of the names of the key exchange actually would like to add another name for credit.

Answer 2

Burnside's Lemma, famously (a) not due to Burnside and (b) not even really a lemma.

(a) is because Burnside himself credits it to Frobenius. (b) is because it is very useful and non-trivial.