This post's subject is Edgar Degas (1834-1917) who left many unfinished paintings. In some cases he signed them, perhaps signifying that he considered them complete enough to his satisfaction.
Examples are shown below. Interestingly, those I found on the Internet had women as subjects. But then, that is true of the majority of his paintings.
I found this in Munich's Neue Pinakothek, which prompted me to write this post. The image is very slightly cropped around the edges. The face seems to be completed. Note the two versions of her left arm and the muddled right hand. His signature is at the lower right.
Essentially monochrome aside for the foliage in the background. The subject's face isn't much more developed than the rest of the painting. Hands are roughly indicated. He signed this.
Not much more than a sketch, yet it has his signature.
Note his working out the room's perspective (it's not quite correct). Again the hands seem to be saved for later development.
Like most other portrait painters Degas chose to complete the face before expending time and materials on the rest.
If this is indeed a study (the title was as I found it on the Web), then it's not really an unfinished painting. I include it here to show Degas' brushwork and use of color.
This was painted later than the others and features his more familiar mature style. Interestingly, whereas it's largely "flat" Degas includes a table that provides as sense of depth by its shape and position.