Is this "travelling salesman problem"/"routing problem" version known?

[Alexander Malkis]

Hello everyone!

Cannot find anything about the following problem. Could anyone help?
Have any decision versions or algorithms been explored?

Let G=(V,E) be an undrected graph (without parallel edges or loops
(v,v)), let W be some subset of V.

(a) Find a shortest path (not necessairly closed) in G that goes through
each element of W at least once.
(b) Find the length of such path from (a).

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Best regards,
Alex.

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