Learn English – Is a question mark needed at the end of a question if the sentence ends with a period or an exclamation mark

A question within a sentence should be preceded by a comma, and end with a question mark.

I am wondering, how long has that fish statue been there?

There are three important issues that this committee must address. What was the chairman doing in that YouTube video? is not among them.

If a question is particularly long or complex, then for clarity it could begin with a capital letter.

In the daydreams of my youth I would look at the clouds and wonder, Will I find happiness and fulfillment soon after getting a business administration degree, or must I amortize my well-being return on investment over the next seven to ten calendar years?

The sentence in the original question ends with a subordinate clause that does not, by itself, ask a question (“within which we can leverage our existing knowledge”). This is modifying a noun phrase that is part of the question (“set of simple computational rules”). Therefore, this subordinate clause is part of the original question, and should end with a question mark.

Putting all of this together, I would punctuate the sentence like this:

The question nagging me is, To what extent can we encapsulate all what we observe in nature into a set of simple computational rules, within which we can leverage our existing knowledge?

(Some of this advice is based on The Chicago Manual of Style 15th Edition §6.55 and §6.71.)

The key question here is whether a proper name whose creators included end punctuation for it must be reproduced with that end punctuation in order to be correctly spelled. If the answer to that preliminary question is yes, then we must proceed to the question that the poster asks about how to accommodate the built-in punctuation when introducing context-appropriate punctuation.

The preliminary question came up repeatedly at the consumer technology magazines where I work, thanks to the effervescent marketing personalities who graced the tech landscape with names like Yahoo!, Astound!, and Utter Bullblap!. Our arbitrary, unsympathetic response has been to treat the alphanumeric components of a proper name as integral to the name, and to treat end punctuation as promotional fluff. Goodbye exclamation points, asterisks, virgules, octothorps, and any other symbols attached to the end of a name to attract the unwary eye and sell more units of the product.

To the extent that exotic punctuation is simply a vehicle for promoting sales or market visibility, dutifully reproducing that punctuation amounts to enlisting oneself and one's publication in the promotional effort—hardly a comfortable position for an independent source of information to be in. That awkwardness helps explain why The Economist in February of 2013 adopted a no-exclamation-points-in-product-names style. I applaud that publication for its decision.

The slippery slope of deferring to the preferences of those who invent proper names, whether for commercial products or for towns and other geographical entities, is evident when you consider the annoying reverse-R favored by the Toys "R" Us toy company; does anyone not in marketing feel strongly that people writing about this company should mirror the R to match the backward proper-name style that the company copyrighted? On a more mundane level, would anyone think to include the period in the name of the restaurant chain Carl's Jr. to yield sentences like "Let's go to Carl's Jr.!" "I had lunch at Carl's Jr.." and "Do you want to go to Carl's Jr.?"? It's really quite absurd.