While there has never been a shortage of so-called " Google killers" -- start-ups aiming to beat the search giant with a better mousetrap -- few have generated fanfare like Cuil. The start-up company's search engine, also called Cuil (pronounced cool), offers an index that's three times larger than any other search engine, its founders say.

Perhaps in anticipation of today's launch, Google on Friday boasted that it has tracked more than a trillion URLs on the Web. And the market leader's position was bolstered a bit today as the new site was unavailable for some periods of time throughout Monday.

Nonetheless, Cuil's launch is bolstered by the backgrounds of those who launched the start-up firm. Anna Patterson, president and COO, worked as an architect of Google search index and led the company's Web page ranking team. Her co-founder and husband Tom Costello, the company's CEO, researched and developed search engine technology at Stanford and IBM.

But despite Cuil's claim that it had indexed 120 billion Web pages and that it provides relevant results based on Web page content analysis, which goes beyond Google's link analysis techniques, some early reviewers questioned whether it can compete with Google.

Danny Sullivan, a blogger with Search Engine Land, acknowledged the pedigrees of the founders of the company. "These people know search," he wrote. "In particular, they know on-the-firing line, heavy duty, industrial strength search. Not only that, they're unleashing what appears to be a comprehensive service that anyone can use."

However, he debunked the company's claim that they use content rather than popularity to link Web pages. Sullivan noted that he tested the search engine with a search for " Harry Potter." The Harry Potter & the Order of the Phoenix movie Web site came up first on Cuil, he noted.

"This is out of thousands of possible pages," he added. "How on earth can Cuil know just from the content on the page itself that the movie site should be in the top results, especially in a web environment where people can (and will) custom tailor content to mislead search algorithms? The answer is link analysis -- counting links and effectively seeing who is pointed at the most. The twist is that it is done by measuring the links from pages relevant to what someone searches on."

He went on to note that Microsoft, Yahoo and Google (the largest search engines today) offer more than just the Web searching that Cuil is providing at launch.

"News search, image search, video search, local search -- these are just some of the verticals that Cuil lacks but which do get used by searchers," Sullivan pointed out. "Not offering these makes Cuil feel too focused on what "old school" search used to be and missing out on the Search 3.0 vertical and blended search revolution that has been going on."

While Cuil has a chance to pick up more search market share than other start-ups targeting search, it is unlikely to threaten Google, he added.

"Google came along at a very special time," he noted. "It had better technology at a time when all the search engines had abandoned improving search, since that was seen as a loss leader. To date, Google is the real exception of a better mousetrap wins.'"

Michael Arrington, a blogger at TechCrunch, added that after testing Cuil for multiple search terms, he found it to be an "excellent search engine," but without the depth or relevancy of Google results. Arrington found that a search for "dog" returned 280 million results on Cuil and 498 million on Google.

"It seems pretty clear that Google's index of web pages is significantly larger than Cuil's unless we're randomly choosing the wrong queries," Arrington noted. "And Cuil's ranking isn't as good as Google's based on the pure results returned from both queries."

However, he did note that Cuil excelled in related categories, which return results that were extremely relevant.

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