What does the absence of punctuation mean in line such as these from ''train train''

How did duke ellington create a new musical style that grew out of the ragtime tradition?

In which quotes does the author use the word "chains" literally? in which quotes does she use the word figuratively?

In 1907, the retrospective on the work of 19th century post-impressionist georges seurat influenced the development of cubism in a radical way through his painting titled, “sunday afternoon on the island of la grande jatte.” ? ?