"invention" is a tricky concept. Edison didn't invent the concept of the light bulb - but he did invent a particular version of it that was commercially viable.

"invention" is a tricky concept. Edison didn't invent the concept of the light bulb - but he did invent a particular version of it that was commercially viable. I don't know the facts, but possibly both 23 and Tesla Corp. developed technological improvements that facilitated commercial viability.