Whether the acquisition of Yelp by Google will attract the scrutiny of regulators largely depends on the regulatory environment, market dynamics, and enforcement priorities at the time of the transaction. While the hypothetical question is interesting to explore, it's important to consider the regulatory environment as it evolves and the complexities of each potential transaction.

A Google purchase of Yelp could raise concerns related to antitrust laws and competition regulations, as it involves the combination of two major players in the online search and local business listing markets. Regulators may assess several factors to determine if the acquisition could result in a substantial lessening of competition or harm to consumers.

Here are some key aspects that regulators might examine:

1. Market Definition: Regulators would likely define the relevant market(s) affected by the acquisition. This could include online search for local businesses, restaurant listings, or more broadly the online local services market. The scope of the relevant market impacts the analysis of competition.

2. Market Concentration: Regulators may assess whether the combined market share of Google and Yelp in the defined market could result in a significant increase in concentration. High market concentration can raise concerns about reduced competition and less choice for consumers.

3. Competitive Effects: Regulators would evaluate if the acquisition would likely lead to reduced innovation, higher prices, or decreased quality in the local services sector. They may consider whether Yelp's independence has played a role in its effectiveness as a competitor and whether the acquisition would reduce this competition.

4. Potential Remedies: If there are perceived antitrust concerns, regulators may suggest remedies to address them, such as divestitures of certain assets, restrictions on how the acquired company's data can be used, or other behavioral commitments to maintain a competitive environment.

5. Global Perspective: Given that both Google and Yelp operate globally, regulators from multiple jurisdictions might be involved in assessing the potential impact of the transaction. Regulators may coordinate to ensure a cohesive approach and consider cross-border effects on competition.

Ultimately, the decision on whether a Google purchase of Yelp would attract regulatory interest is complex and depends on the specific circumstances at the time of the potential transaction, as well as how the law and regulations are applied.