Is it a fashion to omit “is” as in “this a problem that can seem unanswerable.”?

I often see cases that a verb and a preposition are omitted as I posted a question the other day about the omission of “in” in the line, “Perry has had difficulty planting doubt about Romney.”

Today I saw the case “is” is omitted as “this a problem” in the following sentence of aNew York Times article written by Michael P. Lynch under the title, “Reason for Reason."

“Disagreements like this (Evolutionism and Creationism) give rise to an unnerving question: How do we rationally defend our most fundamental epistemic principles? Like many of the best philosophical mysteries, this a problem that can seem both unanswerable and yet extremely important to solve.”

I think it should be “this is a problem.” But if it is the case, can we use “a,” not “the” when “the problem” is modified (or defined) by “that clause”? (though I feel like an article maniac these days.)

Is the omission of “is” today’s fashion, or just a typo?

You may say the author isn’t NYT’s writer unworthy for digging in each phrasing. But according to opinionator @nytimes.com, Michael Lynch is a contemporary philosopher, who must be the master of logic and rhetoric.

Solution 1:

That usage is just not acceptable. There's no way that was intentional -- it's clearly a typo.

Solution 2:

Looks like a typo to me. I don't recognize the sentence as grammatical. When you leave out the specifics, the sentence seems to be missing an 'is'.

Like X, this [is] a problem that can seem Y and Z.

Without the 'is' there, the sentence has no main verb.