Last Tuesday, computer science department chair Joan Feigenbaum received an unpleasant reminder in her mailbox. Scanning two new postcards from the computer science departments of University of Illinois and Johns Hopkins University, she saw 17 headshots of new faculty members.

Finding newsletters of this sort in her mailbox is not an unusual occurrence. But while University of Illinois hired six new faculty members and Johns Hopkins hired 11 this past year alone, Yale’s computer science department has not seen an increase in faculty within the past 10 years. Feigenbaum wonders if she will ever be able to send out newsletters like these.

Computer science is now the seventh most popular major at Yale, and according to the Office of Institutional Research website, the number of junior and senior computer science majors has doubled since 2011. The number of undergraduate course registrations for computer science classes has gone from 600 to 1,400 undergraduates. And these numbers do not include the increase in students from this year, which are even larger, Feigenbaum said. Meanwhile, the computer science faculty size has not grown larger than 20 faculty members since 1989, a year when just over 400 undergraduate students were registered for computer science courses. Feigenbaum and other faculty voiced their frustrations with the lack of growth and said they feared the Yale computer science department is slipping behind its peer institutions’ departments.

“The degree to which we are understaffed has all sorts of confounding problems,” professor of computer science Bryan Ford said. “All of the specializations in CS are taking a toll because we really only have one person in each area, and that is the norm in this department.”

Ford said Yale is slipping behind many other schools like Princeton, which have no upper-bound limit on the amount of offers they are able to make in a single year. In contrast, over the past five years, when the Yale computer science department has been given the opportunity to hire, it has only been allowed to make an offer for one slot. According to Ford, that policy — what the department calls a slot-limited model — forces the computer science department to go into the process of hiring with the expectation that, at most, only one candidate will be hired. If the one or two candidates whom they are courting reject the offer, they are left with no one. Ford said the department needs to be making at least 10 offers every year in order to keep up with schools like Princeton.

According to Ford, last year Princeton interviewed 25 candidates and made offers to 12 candidates, four of whom accepted. Those low acceptance rates are surprising, considering that Princeton’s department is eighth in the nation, according to U.S. News & World Report, Ford said. Princeton’s department, like all computer science departments, is limited by the pool of qualified candidates, but not a set number of slots — what Yale computer science professors call a “candidate-limited model.” Computer science departments are not only competing for faculty applicants with their peer institutions’ departments — they are also competing with big industry companies like Google and Microsoft, Ford added.

STRAINED FACULTY

Of the 13 most popular majors at Yale, computer science is the only one without its graduate program on U.S. News & World Report’s top 10 ranked Best Graduate Schools list, which is often accepted as an overall metric of department quality, according to Ford. Yale is ranked 20th on the list.

The average faculty size for the current top 10 computer science departments in the nation is 67 faculty members — Yale’s department, coming in at 20 faculty members, is less than a third of that size. The next top 10 universities have an average of 39 faculty members, still almost double that of Yale’s faculty.

According to Ford, even though the University’s department has top-notch faculty, in a field that is growing as fast as computer science, having a few of the very best people is just not enough. Universities need both quantity and quality in faculty.

In addition, those schools that ranked in the top 11 to 20 — five schools were tied for the 20th spot — have shown an average growth rate of 21 percent over the past 10 years. Meanwhile, Yale’s growth rate is virtually non-existent, Ford said.

Given how poorly Yale compares to its peers in faculty size, the University only has one way to catch up — it must convert from a slot-limited to candidate-limited model, Ford said.

“That would be clearly the right thing to do, and certainly Yale could afford it,” he said. “It is not like the money doesn’t exist, it just needs to be done.”

Feigenbaum said every time Yale has been given the opportunity to hire someone, it has acquired an excellent professor. She said the department has presented its case for new faculty to the administration again and again, but the administration has consistently responded by saying it cannot give them more professors — it is restrained due to financial reasons.

The growth problem is not unique to computer science, Feigenbaum said, noting that most FAS departments are likely experiencing the same pushback against faculty growth because of the University’s financial situation. But she said the computer science department is most vocal because an unprecedented number of undergraduates have expressed interest in the major and the department’s courses.

Computer science professor Holly Rushmeier told Feigenbaum that she would like to teach a new class entitled “From Physical to Virtual and Back Again.” The course would focus on converting digital models to physical models through 3-D printing. But Rushmeier cannot teach the course now because the department needs her to teach Computer Science 201 — “Introduction to Computer Science” — one of the core courses of the major.

Ford said this year’s increase in diversity of computer science classes is an improvement for the department, but he added that continuing to grow the department’s course diversity will not be possible without additional faculty.

Richard Yang, who teaches two highly regarded networking courses at Yale — CPSC 433/533 and CPSC 434/534 — is the only one among faculty who specializes in networking. Since he is on leave this semester, no networking courses are being taught, Feigenbaum said.

Daniel Spielman ’92, a professor in the computer science, mathematics and applied mathematics departments and a MacArthur Genius Grant recipient, is the only person at Yale specializing in algorithms. He said many of the computer science specialties only have one faculty member, making it difficult to attract graduate students.

Spielman said last year’s efforts to attract graduate students fell short — none of the three he admitted chose Yale. They instead chose MIT, Stanford and Princeton. Spielman said he was most upset by the choice of Princeton because in the past, Yale’s computer science department was considered to be better than Princeton’s.

“But now [Princeton] has five or six young faculty in my field that he can work with,” Spielman said. “So, what can I say? Maybe, he made the right decision. It’s upsetting because we used to be pretty comparable. Now, we look like a less exciting place to land. The graduate students [who want to specialize in algorithms] can ask me ‘Well what happens if you leave?’ ‘Well then you are screwed.’”

GRADUATE QUALMS

In 1989, Yale had over 90 PhD candidates in computer science. Two years ago, there were fewer than 50 graduate students. Ford said these low numbers result in fewer teaching fellows for undergraduates, which means most of the large lectures do not break down into smaller sections.

Spielman said this increase in the number of undergraduate students — without an accompanying increase in faculty or TFs — has led to less satisfactory class experiences. Undergraduates have less of an opportunity to get to know each other and the professors. According to Spielman, there are no longer sufficient resources to target students who need additional help or to cater to those who need more challenging material.

According to professor of computer science Julie Dorsey, because graduate students are funded by individual faculty grants, having fewer faculty means fewer graduate students .

“Regardless of how Yale reached its current status, in order to remain one of the world’s top educational institutions in the long run, Yale needs to have strong departments teaching the topics that its students most want and need to study,” Dorsey said. “Computer science is fundamental to a liberal arts education.”

Spielman said he fears that without more faculty, the department will have to change the structure of the major entirely. As of now, each senior completes an individual project under the guidance of a department advisor, with whom they meet at least once a week. Each faculty member can only handle so many students, and an increase in undergraduate enrollment in the major would mean getting rid of the mentorship requirement.

According to Feigenbaum, without guaranteed growth, the department may have to come up with some interesting alternatives — like the recently proposed possibility of importing Harvard’s well-known CS50 course to Yale. The joint learning experience would involve using Harvard professor David Malan’s video courses with a Yale professor supplementing his lectures.

Last semester, Yupei Guo ’17 walked into Computer Science 112 , “Introduction to Programming,” excited to see what the course had to offer. She found her answer immediately after scanning the auditorium — too many students. She ultimately decided against the course because of its overwhelming enrollment.

“You literally had to fight for a seat in the class,” Guo said. “Students were sitting in the aisles.”

At Carnegie Mellon University in Pittsburgh, Pa., sophomore Billy Matchen sat in a room with fewer than 20 other students, engaged in a computer science recitation section. CMU’s computer science department is considered one of the best in the country.

Matchen’s professor is one of almost 140 in CMU’s computer science department.

Correction: Oct. 22

A previous version of this article misstated the number of Yale College majors that fall within the top 10 ranked Best Graduate Schools by U.S. News and World Report as 15 instead of 13. The article also misrepresented computer science professor Bryan Ford’s view of the slot-limited model.