Less than two years after Google dismissed two researchers who criticised the biases built into AI systems, the company has fired a researcher who questioned a paper it published on the abilities of a specialised type of AI used in making computer chips.

Satrajit Chatterjee, 43, led a team of scientists in challenging the paper that appeared in Nature and said computers were able to design parts of a computer chip faster and better than humans.

Chatterjee was fired in March, after Google said it would not publish a paper that rebutted some of the claims made in the Nature article, said four people familiar with the situation. Google confirmed that Chatterjee had been “terminated with cause”.

Chatterjee’s dismissal was the latest example of discord in and around Google Brain, an AI research group considered to be a key to the company’s future. After spending billions of dollars to hire top researchers and create new kinds of computer automation, Google has struggled with a wide variety of complaints about how it builds, uses and portrays those technologies.

In December 2020, Google fired one of the leaders of its Ethical AI team, Timnit Gebru, after she criticised the company’s approach to minority hiring and pushed to publish a research paper that pointed out flaws in a new type of AI system for learning languages. A few months later, the company fired the other head of the team, Margaret Mitchell, who publicly denounced Google’s handling of the situation with Gebru.

The paper in Nature, published last June, promoted a technology called reinforcement learning, which it said could improve the design of computer chips. The technology was hailed as a breakthrough for AI and a vast improvement to existing approaches to chip design. Google said it used this technique to develop its own chips for AI computing.

Google had been working on applying the machine learning technique to chip design for years, and it published a similar paper a year earlier. Around that time, Google asked Chatterjee, who has a doctorate in computer science from the University of California, Berkeley, US, and had worked as a research scientist at Intel, to see if the approach could be sold or licensed to a chip design company.

But Chatterjee expressed reservations in an internal email about some of the claims and questioned whether the technology had been rigorously tested.

While the debate about that research continued, Google pitched another paper to Nature. It made some adjustments to the earlier paper and removed the names of two authors, who had worked closely with Chatterjee.

When the newer paper was published, some Google researchers were surprised. They believed it had not followed a publishing approval process that Jeff Dean, the company’s senior vice-president, said was necessary in the aftermath of Gebru’s firing.

Google and one of the two lead authors, Anna Goldie, who wrote it with Azalia Mirhoseini, said the changes from the earlier paper did not require the full approval process. Google allowed Chatterjee and some internal and external researchers to work on a paper that challenged some of its claims.

The team submitted the rebuttal paper to a resolution committee for publication approval. Months later, the paper was rejected.

The researchers who worked on the rebuttal paper said they wanted to escalate the issue to Sundar Pichai and Alphabet’s board of directors. Soon after, Chatterjee was informed that he was no longer an employee, the people said.

Goldie said Chatterjee had asked to manage their project in 2019 and they had declined. When he later criticised it, she said, he could not substantiate his complaints and ignored the evidence they presented in response. “Sat Chatterjee has waged a campaign of misinformation against me and Azalia for over two years now,” Goldie said in a written statement.

Laurie M. Burgess, Chatterjee’s attorney, said it was disappointing that “certain authors of the Nature paper are trying to shut down scientific discussion by defaming and attacking Dr Chatterjee for simply seeking scientific transparency.” Burgess also questioned the leadership of Dean, one of 20 co-authors of the paper.

Dean did not respond to a request for comment.

NYTNS