UT Computer Science is excited to welcome four new faculty members coming to campus in 2014. They all have incredibly impressive credentials and research experience, and we’re extremely grateful that they have chosen to join our family.

We encourage you to learn more about our new faculty and extend a warm Longhorns welcome when you see them on campus.

Işil Dillig - Assistant Professor

Ph.D. 2011, Stanford

Program Analysis
Programming Langauges
Automated Logical Reasoning

Işil Dillig is a graduate of Stanford University, where she received her Ph.D. in computer science in 2011. After completing her Ph.D., Işil worked as an assistant professor at the College of William and Mary in Williamsburg, Virginia, and later as a researcher at Microsoft Research in Cambridge, UK.

Işil’s research interests include program analysis, programming languages, and automated logical reasoning. The main goal of her research is to make software systems more reliable, secure, and easier to build in a robust way. Her recent research has addressed scalable techniques for static reasoning about pointers, path- and context-sensitive analysis, container data structures, the interplay between over- and under-approximations of program behavior, and constraint solving and simplification techniques that enable more efficient analysis algorithms.

Thomas Dillig - Assistant Professor

Ph.D. 2012, Stanford

Program Verification
Automatic Constraint Solving

Thomas Dillig received his Ph.D. from Stanford University in 2012, with a dissertation on “A Modular and Symbolic Approach to Static Program Analysis.” Previously he was an assistant professor at the College of William & Mary and a senior lecturer at University College London.

Tom’s main research interests are program verification and automatic constraint solving. The end goal of his work is to develop new techniques to build reliable and provably correct software systems and make costly program errors a thing of the past.

Tom has worked on several software projects, including SAIL and SATURN. SAIL is a front-end for program analysis systems that provides a two-level representation, consisting of both a language-specific high-level intermediate language as well as a low-level, language-independent representation. SATURN is a program analysis system. The goal of the Saturn project is to statically and automatically verify properties of large (meaning multi-million line) software systems.

Eric Price - Assistant Professor

Ph.D. 2013, MIT

Sparse Recovery
Compressive Sensing
Sparse Fourier Sampling

Eric Price completed his graduate studies at the Massachusetts Institute of Technology, receiving a Ph.D. in computer science in 2013. Since then, he has been a postdoctoral research fellow at the Simons Institute for the Theory of Computing and the IBM Almaden Research Center.

Eric's research focuses on making the Fast Fourier Transform, one of the most fundamental algorithms in a variety of disciplines, even faster. Eric’s thesis shows how the sparsity of the Fast Fourier Transform can lead to substantially faster algorithms.

Eric’s research was featured in Technology Review’s TR10 list of 10 breakthrough technologies of 2012, and his thesis was a recipient of the George M. Sprowls award for best doctoral thesis in computer science at MIT.

Eric also co-created NewsDiffs, which tracks post-publication changes to online news articles. Almost half of all news articles are silently changed after being posted online, and NewsDiffs provides a way to reference old versions and see the changes that have occurred. NewsDiffs has been cited several times by the New York Times to reference old versions of its own articles.

Etienne Vouga - Assistant Professor

Ph.D. Columbia University 2012

Computer Graphics
Applied Mathematics
The Geometry of Physics 

Etienne Vouga earned his Ph.D. from Columbia University in 2012, where he researched physical simulation as part of Columbia University’s Computer Graphics Group. He is now spending one year as a postdoctoral fellow at Harvard University, working in L. Mahadevan’s Applied Mathematics Group. He will join UT Computer Science as an Assistant Professor in Fall 2014.

Etienne studies the geometry of the physics of everyday materials—how hair twists and curls, the way cloth wrinkles and folds when it is wrung out or balled up, and the relationship of a stone building’s shape to its stability. By blending computer science, applied physics, geometry, and numerical methods, he turns insights about the geometry of these materials into more accurate and efficient computer algorithms for simulating them, and for interactively designing objects built from these materials that takes into account not only the intended form but also the intended function.

 Special effects studios Disney and Weta Digital have used Etienne’s work on cloth and hair simulation in movies such as Tangled and The Hobbit. He was awarded an NSF Postdoctoral Research Fellowship in applied mathematics for the year 2013-2014, and his work on Asynchronous Contact Mechanics, a framework for simulating the behavior of cloth under contact, was featured in the 2012 Communications of the ACM Research Highlights.

This is the beginning of a series of four pieces that will feature personal profiles of the new faculty at UT Computer Science.

If you’ve seen movies like Tangled and the Hobbit you might have been

unknowingly exposed to new UT Computer Science Assistant Professor Etienne Vouga. That’s because companies like Disney and Weta Digital have used his work in the study of geometry and physics of every day material. 

Etienne’s work stems from his interest in computers at a very young age.  He would play computer games, hack them and think of ways to make them better. This interest is what eventually led him to receive his BA in mathematics and computer science from Rice University, and his Ph.D. in computer science from Columbia University.

Throughout his education, research played a large role. Etienne specifically studied the geometry of the physics of everyday materials and what causes these materials to react in a certain way. Examples of this include how hair twists and curls, the way cloth wrinkles and folds, and the relationship of a stone building’s shape to its stability.

“I study the geometry of these objects and come up with a way to approximate this behavior,” Etienne said.  “From there that let’s you translate the physical laws into algorithms on the computers.” 

This is the second of a series of four pieces that will feature personal profiles of the new faculty at UT Computer Science.

His research and the algorithms he has created have been used to make cloth and hair movement look more realistic in films.  His work of a framework for simulating the behavior of cloth under contact was featured in the 2012 Communications of the Association for Computing Machinery (ACM) Research highlights.

The research and work he has done prior to his time at UT were leading factors in what drew him to make the decision to be a member of the computer science faculty.  He says specifically that UT’s Institute for Computational and Engineering Science played a part in the decision.

“The resources available at ICES compliment my own research,” Etienne said. “It is based in computer science and computer graphics but frequently relies on and has applications for computational mechanics engineering and applied math.”

When Etienne is not teaching students physical simulations for computer graphics, he has been working with ICES to brainstorm the idea of ways to 3D print a human liver. Working with ICES provides the opportunity to have strong collaborations between people of different disciplines to work on solving more problems.

In the future Etienne hopes to be able to use his research and his work from UT to be able to give people the tools they need to completely design the world around them.

“I think we are moving toward a world where you’ll be able to be in complete control of everything around you and the computer will be able to help you do that.”

A UTCS programming team finished second at this year's ACM International Collegiate Programming Contest (ACM-ICPC) regional competition. The team of Arnav Sastry, Daniel Talamas, and Jaime Rivera beat approximately 60 different teams competing in the South Central U.S region of the contest.

ACM-ICPC is an annual programming competition among universities all over the world. The contest, sponsored by IBM, hosts around 2,300 universities from over 90 countries across six continents every year.

A total of four UT teams entered the competition and all finished within the top seven. The teams solved six and seven out of nine problems. Seven was the highest number of problems solved by any team.

The UTCS teams are sponsored and organized by faculty members Etienne Vouga, Glenn Downing, and Shyamal Mitra.

The first place team from Rice University will continue onto the world finals in Thailand in 2016.

The UT students that participated in the competition were: Alex Meed, Arnav Sastry, Brady Zhou, Brian Richer, Chris Denny, Daniel Talamas, Jaime Rivera, Jesse Mao, Jon Lee, Naeem Quddus, Robert Faulk, and Veronica Gunn.

College of Natural Sciences | Point of Discovery

As the summer movie season kicks into high gear, we talk with a scientist about some of the challenges in simulating the way everyday objects behave on the big screen through computer generated imagery (CGI). Etienne Vouga's computer simulations have helped bring to life a wizard's hair in The Hobbit and clothing in Tangled.

Listen to Etienne Vouga's interview with Marc Airhart at https://cns.utexas.edu/news/why-is-cgi-in-the-movies-still-so-hard.

See examples of some of Vouga's simulations below.

UT Computer Science is excited to welcome four new faculty members coming to campus in 2014. They all have incredibly impressive credentials and research experience, and we’re extremely grateful that they have chosen to join our family.

We encourage you to learn more about our new faculty and extend a warm Longhorns welcome when you see them on campus.

Işil Dillig - Assistant Professor

Ph.D. 2011, Stanford

Program Analysis
Programming Langauges
Automated Logical Reasoning

Işil Dillig is a graduate of Stanford University, where she received her Ph.D. in computer science in 2011. After completing her Ph.D., Işil worked as an assistant professor at the College of William and Mary in Williamsburg, Virginia, and later as a researcher at Microsoft Research in Cambridge, UK.

Işil’s research interests include program analysis, programming languages, and automated logical reasoning. The main goal of her research is to make software systems more reliable, secure, and easier to build in a robust way. Her recent research has addressed scalable techniques for static reasoning about pointers, path- and context-sensitive analysis, container data structures, the interplay between over- and under-approximations of program behavior, and constraint solving and simplification techniques that enable more efficient analysis algorithms.

Thomas Dillig - Assistant Professor

Ph.D. 2012, Stanford

Program Verification
Automatic Constraint Solving

Thomas Dillig received his Ph.D. from Stanford University in 2012, with a dissertation on “A Modular and Symbolic Approach to Static Program Analysis.” Previously he was an assistant professor at the College of William & Mary and a senior lecturer at University College London.

Tom’s main research interests are program verification and automatic constraint solving. The end goal of his work is to develop new techniques to build reliable and provably correct software systems and make costly program errors a thing of the past.

Tom has worked on several software projects, including SAIL and SATURN. SAIL is a front-end for program analysis systems that provides a two-level representation, consisting of both a language-specific high-level intermediate language as well as a low-level, language-independent representation. SATURN is a program analysis system. The goal of the Saturn project is to statically and automatically verify properties of large (meaning multi-million line) software systems.

Eric Price - Assistant Professor

Ph.D. 2013, MIT

Sparse Recovery
Compressive Sensing
Sparse Fourier Sampling

Eric Price completed his graduate studies at the Massachusetts Institute of Technology, receiving a Ph.D. in computer science in 2013. Since then, he has been a postdoctoral research fellow at the Simons Institute for the Theory of Computing and the IBM Almaden Research Center.

Eric's research focuses on making the Fast Fourier Transform, one of the most fundamental algorithms in a variety of disciplines, even faster. Eric’s thesis shows how the sparsity of the Fast Fourier Transform can lead to substantially faster algorithms.

Eric’s research was featured in Technology Review’s TR10 list of 10 breakthrough technologies of 2012, and his thesis was a recipient of the George M. Sprowls award for best doctoral thesis in computer science at MIT.

Eric also co-created NewsDiffs, which tracks post-publication changes to online news articles. Almost half of all news articles are silently changed after being posted online, and NewsDiffs provides a way to reference old versions and see the changes that have occurred. NewsDiffs has been cited several times by the New York Times to reference old versions of its own articles.

Etienne Vouga - Assistant Professor

Ph.D. Columbia University 2012

Computer Graphics
Applied Mathematics
The Geometry of Physics 

Etienne Vouga earned his Ph.D. from Columbia University in 2012, where he researched physical simulation as part of Columbia University’s Computer Graphics Group. He is now spending one year as a postdoctoral fellow at Harvard University, working in L. Mahadevan’s Applied Mathematics Group. He will join UT Computer Science as an Assistant Professor in Fall 2014.

Etienne studies the geometry of the physics of everyday materials—how hair twists and curls, the way cloth wrinkles and folds when it is wrung out or balled up, and the relationship of a stone building’s shape to its stability. By blending computer science, applied physics, geometry, and numerical methods, he turns insights about the geometry of these materials into more accurate and efficient computer algorithms for simulating them, and for interactively designing objects built from these materials that takes into account not only the intended form but also the intended function.

Special effects studios Disney and Weta Digital have used Etienne’s work on cloth and hair simulation in movies such as Tangled and The Hobbit. He was awarded an NSF Postdoctoral Research Fellowship in applied mathematics for the year 2013-2014, and his work on Asynchronous Contact Mechanics, a framework for simulating the behavior of cloth under contact, was featured in the 2012 Communications of the ACM Research Highlights.

This is the beginning of a series of four pieces that will feature personal profiles of the new faculty at UT Computer Science.

If you’ve seen movies like Tangled and the Hobbit you might have been

unknowingly exposed to new UT Computer Science Assistant Professor Etienne Vouga. That’s because companies like Disney and Weta Digital have used his work in the study of geometry and physics of every day material. 

Etienne’s work stems from his interest in computers at a very young age.  He would play computer games, hack them and think of ways to make them better. This interest is what eventually led him to receive his BA in mathematics and computer science from Rice University, and his Ph.D. in computer science from Columbia University.

Throughout his education, research played a large role. Etienne specifically studied the geometry of the physics of everyday materials and what causes these materials to react in a certain way. Examples of this include how hair twists and curls, the way cloth wrinkles and folds, and the relationship of a stone building’s shape to its stability.

“I study the geometry of these objects and come up with a way to approximate this behavior,” Etienne said.  “From there that let’s you translate the physical laws into algorithms on the computers.” 

This is the second of a series of four pieces that will feature personal profiles of the new faculty at UT Computer Science.

His research and the algorithms he has created have been used to make cloth and hair movement look more realistic in films.  His work of a framework for simulating the behavior of cloth under contact was featured in the 2012 Communications of the Association for Computing Machinery (ACM) Research highlights.

The research and work he has done prior to his time at UT were leading factors in what drew him to make the decision to be a member of the computer science faculty.  He says specifically that UT’s Institute for Computational and Engineering Science played a part in the decision.

“The resources available at ICES compliment my own research,” Etienne said. “It is based in computer science and computer graphics but frequently relies on and has applications for computational mechanics engineering and applied math.”

When Etienne is not teaching students physical simulations for computer graphics, he has been working with ICES to brainstorm the idea of ways to 3D print a human liver. Working with ICES provides the opportunity to have strong collaborations between people of different disciplines to work on solving more problems.

In the future Etienne hopes to be able to use his research and his work from UT to be able to give people the tools they need to completely design the world around them.

“I think we are moving toward a world where you’ll be able to be in complete control of everything around you and the computer will be able to help you do that.”

A UTCS programming team finished second at this year's ACM International Collegiate Programming Contest (ACM-ICPC) regional competition. The team of Arnav Sastry, Daniel Talamas, and Jaime Rivera beat approximately 60 different teams competing in the South Central U.S region of the contest.

ACM-ICPC is an annual programming competition among universities all over the world. The contest, sponsored by IBM, hosts around 2,300 universities from over 90 countries across six continents every year.

A total of four UT teams entered the competition and all finished within the top seven. The teams solved six and seven out of nine problems. Seven was the highest number of problems solved by any team.

The UTCS teams are sponsored and organized by faculty members Etienne Vouga, Glenn Downing, and Shyamal Mitra.

The first place team from Rice University will continue onto the world finals in Thailand in 2016.

The UT students that participated in the competition were: Alex Meed, Arnav Sastry, Brady Zhou, Brian Richer, Chris Denny, Daniel Talamas, Jaime Rivera, Jesse Mao, Jon Lee, Naeem Quddus, Robert Faulk, and Veronica Gunn.

College of Natural Sciences | Point of Discovery

As the summer movie season kicks into high gear, we talk with a scientist about some of the challenges in simulating the way everyday objects behave on the big screen through computer generated imagery (CGI). Etienne Vouga's computer simulations have helped bring to life a wizard's hair in The Hobbit and clothing in Tangled.

Listen to Etienne Vouga's interview with Marc Airhart at https://cns.utexas.edu/news/why-is-cgi-in-the-movies-still-so-hard.

See examples of some of Vouga's simulations below.

On Wed, 24 May 2017, the UT Competitive Programming team competed at the ACM-ICPC World Finals, the oldest, largest, and most prestigious programming contest in the world, at the South Dakota School of Mines & Technology in Rapid City, South Dakota.

The competition consisted of teams from 133 regions across the world (approx. 532 students) trying to solve 12 programming problems of varying levels of difficulty in 5 hrs and 20 min. The first-place team, St. Petersburg University, solved 10 problems. UT solved 4 problems and tied with 53 other teams for 56th place. In total, a record 50,145 students competed in regional competitions worldwide, and of the 532 students who made it to the world finals, the UT team of three students finished in the top half.

Teams consist of three students. The students on the UT team were Alex Meed, Brian Richer, and Supawit Chockchowwat; the faculty coaches were Etienne Vouga, Glenn Downing, and Shyamal Mitra.

UT qualified for the world finals this year by winning the South Central USA region, which includes Texas, Oklahoma, and Louisiana and includes over 60 teams from 25+ schools. UT has been competing in the Regionals since 1997, and places in the top 5 almost every year. In 2014, one of our four teams took 2nd place at the regionals. In 2015, one of our four teams took 2nd place again, but all four of our teams were in the top seven. In 2016, our four teams swept the regionals with 1st, 2nd, 3rd, and 4th place. Qualification for the world finals this year followed a concerted effort to improve UT's performance at the contests, including the creation of a new elective, CS104c: Competitive Programming, taught by the faculty coaches and club officers.

The ACM International Collegiate Programming Contest (ICPC) is the premiere global programming competition conducted by and for the world’s universities. The competition operates under the auspices of ACM, is sponsored by IBM, and is headquartered at Baylor University. For nearly four decades, the ICPC has grown to be a game-changing global competitive educational program that has raised aspirations and performance of generations of the world’s problem solvers in the computing sciences and engineering.

The ICPC traces its roots to a competition held at Texas A&M in 1970 hosted by the Alpha Chapter of the UPE Computer Science Honor Society. The idea quickly gained popularity within the United States and Canada as an innovative initiative to raise the aspirations, performance, and opportunity of the top students in the emerging field of computer science. The contest fosters creativity, teamwork, and innovation in building new software programs, and enables students to test their ability to perform under pressure.

The contest evolved into a multi-tier competition with the first Finals held at the ACM Computer Science Conference in 1977. Operating under the auspices of ACM and headquartered at Baylor University since 1989, the contest has expanded into a global network of universities hosting regional competitions that advance teams to the ACM-ICPC World Finals.

Since IBM became a sponsor in 1997, ICPC participation has increased by more than 2000%.

This year ICPC Regional participation included 46,381 of the finest students and faculty in computing disciplines from 2,948 universities in 103 countries on six continents. A record 50,145 students and 5,073 coaches competed in ICPC and ICPC-assisted competitions this year, setting new records in participation.

On Sat, 4 Nov 2017, the UT Competitive Programming team won the ACM-ICPC South Central USA Regional Competition at Baylor University in Waco, Texas. The winning team, consisting of Arnav Sastry (senior), Daniel Talamas (senior), and Ethan Arnold (junior), will compete in the ACM-ICPC World Finals this coming April in Bejing, China.

The competition consisted of 70+ teams from 25+ schools (approx. 225 students) from across Texas, Louisiana, and Oklahoma. UT Austin's top team solved ten problems, more than any other team. Due to technical problems with the automated contest judge, the final rankings of the other teams are still uncertain; provisionally UT Dallas came in 2nd and solved nine problems, and Texas A&M came in 3rd and solved eight problems. UT Austin's other three teams came in 5th (Aditya Durvasula, Ho-Jae Jung, Jie Hao Liao), 8th (Alex Meed, Celik Savk, Supawit Chockchowwat), and 17th (Alex Hong, Hoang Dinh, Miguel Obregon).

UT has been competing in the Regionals since 1997. In 2014, one of the four teams took 2nd place. In 2015, one of the four teams took 2nd place again. In 2016, the four teams swept the regionals with 1st, 2nd, 3rd, and 4th place. The UT team has seen marked improvement since the creation of a new elective, CS104c: Competitive Programming, taught by the faculty coaches Etienne Vouga and Glenn Downing and the student officers of the UT Competitive Programming Club.

The ACM International Collegiate Programming Contest (ICPC) is the premier global programming competition conducted by and for the world’s universities. The competition operates under the auspices of ACM, is sponsored by IBM, and is headquartered at Baylor University. For nearly four decades, the ICPC has grown to be a game-changing global competitive educational program that has raised aspirations and performance of generations of the world’s problem solvers in the computing sciences and engineering. The ICPC traces its roots to a competition held at Texas A&M in 1970 hosted by the Alpha Chapter of the UPE Computer Science Honor Society. The idea quickly gained popularity within the United States and Canada as an innovative initiative to raise the aspirations, performance, and opportunity of the top students in the emerging field of computer science.

The contest evolved into a multi-tier competition with the first Finals held at the ACM Computer Science Conference in 1977. Operating under the auspices of ACM and headquartered at Baylor University since 1989, the contest has expanded into a global network of universities hosting regional competitions that advance teams to the ACM-ICPC World Finals. Since IBM became a sponsor in 1997, ICPC participation has increased by more than 2000%. This year ICPC Regional participation included 46,381 of the finest students and faculty in computing disciplines from 2,948 universities in 103 countries on six continents. A record 50,145 students and 5,073 coaches competed in ICPC and ICPC-assisted competitions this year, setting new records in participation.

The contest fosters creativity, teamwork, and innovation in building new software programs, and enables students to test their ability to perform under pressure. Quite simply, it is the oldest, largest, and most prestigious programming contest in the world.

On Thu, 19 Apr 2018, the UT Competitive Programming team competed at the ACM-ICPC World Finals at Peking University in Beijing, China.

The competition consisted of teams from 140 regions (approx. 420 students) trying to solve 11 problems in 5 hrs and 20 min. The first-place team, Moscow State University, solved 9 problems. UT solved 4 problems and tied with 42 other teams for 56th place.

Teams consist of three students. The students on the UT team were Arnav Sastry ('18), Ethan Arnold ('19), and Daniel Talamas ('18); the faculty coaches were Etienne Vouga and Glenn Downing.

UT qualified for the world finals by winning the South Central USA region, which includes Texas, Oklahoma, and Louisiana and includes over 60+ teams from 25+ schools. UT has been competing in the Regionals since 1997, and places in the top 5 almost every year. In 2014, one of our four teams took 2nd place at the regionals. In 2015, one of our four teams took 2nd place again, but all four of our teams were in the top seven. In 2016, our four teams swept the regionals with 1st, 2nd, 3rd, and 4th place. Qualification for the world finals this year followed a concerted effort to improve UT's performance at the contests, including the creation of a new elective, CS104c: Competitive Programming, taught by the faculty coaches and club officers.

The ACM International Collegiate Programming Contest (ICPC) is the premier global programming competition conducted by and for the world's universities. The ICPC is affiliated with the ICPC Foundation, enjoys the auspices of ACM, and is headquartered at Baylor University. For over four decades, the ICPC has grown to be a game-changing global competitive educational program that has raised aspirations and performance of generations of the world's problem solvers in the computing sciences and engineering.

In ICPC competitions, teams of three students represent their university in multiple levels of regional competition. Volunteer coaches prepare their teams with intense training and instruction in algorithms, programming, and teamwork strategy. Several ICPC universities and ICPC volunteers provide online judging systems to all free of charge. Top teams from regional competition advance to the final round. This year's regional competitions advanced teams to the World Championship round - the 2018 ACM-ICPC World Finals hosted by Peking University - which was conducted on 19 April, 2018 in Beijing, China.

The ICPC traces its roots to a competition held at Texas A&M in 1970 hosted by the Alpha Chapter of the UPE Computer Science Honor Society. The idea quickly gained popularity within the United States and Canada as an innovative initiative to raise the aspirations, performance, and opportunity of the top students in the emerging field of computer science.

The contest evolved into a multi-tier competition with the first Finals held at the ACM Computer Science Conference in 1977. Operating under the auspices of ACM and headquartered at Baylor University since 1989, the contest has expanded into a global network of universities hosting regional competitions that advance teams to the ACM-ICPC World Finals.

In the past 20 years alone, ICPC participation has increased by more than 2000%. Last year, ICPC Regional participation included 49,935 of the finest students and faculty in computing disciplines from 3,098 universities in 111 countries on six continents. A record 53,446 students and 5,411 coaches competed in ICPC and ICPC-assisted competitions last year, setting new records in participation.

The contest fosters creativity, teamwork, and innovation in building new software programs, and enables students to test their ability to perform under pressure. Quite simply, it is the oldest, largest, and most prestigious programming contest in the world.

The world is made up of shapes of all kinds, from boxy cubes to perfect spheres and everything in between. Some shapes work best for certain applications; for example, only a few configurations will lead to a stable building.

Computer science assistant professor Etienne Vouga’s research in physical simulation and geometry processing takes these complex shapes, turns them into a simpler type of geometry that a computer can understand, then uses computer algorithms to improve real-world applications such as architecture and 3D printing.

In order to allow computers to simulate these systems, the smooth, continuous geometry of the real world must be approximated by breaking the curves and surfaces into a finite amount of points.

“Geometry in the real world is extremely complex: there’s lots of details in geometry, there’s lots of sharp features and small details,” Vouga said. “If you try to create a computer algorithm that deals with real-world geometry, it just isn’t tractable, there’s just too much data and too much complexity.”

For example, in order to simulate a perfect sphere with infinitely many points on a computer, it must be approximated as a polyhedron, or many-sided object, with its smooth curves broken up by an amount of points that the computer can handle. However, many formulas in math and physics require the geometry to be smooth and won't work if you try to apply them directly to discrete, or “chunky,” objects. Researchers such as Vouga study new formulas that can handle this discontinuous geometry, called discrete differential geometry.

A major challenge is making sure that any formulas or mathematical descriptions of the approximated object reflect reality. Sometimes, according to Vouga, formulas that approximate real-world objects can break down as more detail is added to a computer simulation.

However, there’s a trade-off to more detailed approximations: more accuracy costs more computational resources. The key is to balance an accurate representation of the object with using less information and processing power, Vouga said.

“You want to have this knob that you can tune so that the more (computational resources) budget you can allow, the better your answer gets,” he said. “The hallmark of a good algorithm in discrete differential geometry is that this knob is in place and works correctly.”

In the past, Vouga and his fellow researchers have used discrete differential geometry to turn the physics of buildings into algorithms that can predict what building shapes will and won’t hold up. By simplifying the geometry, computers can handle the formulas in a shorter amount of time, allowing these algorithms to be used in software programs that architects can use to try out different shapes and understand how they would work in the real world.

For example, skyscrapers are most commonly built with concrete strengthened by steel reinforcing bars, but architects want building techniques that don’t use these materials, according to Vouga. After about a century, the steel begins to corrode within the concrete and the building becomes less stable. Buildings made from other materials, such as stone or glass, would last longer and cost less to construct, Vouga said.

“For these kinds of buildings, the algorithm I’ve designed can be used to figure out what geometries are possible and what geometries are not possible for constructing these things,” he said.

More recently, Vouga has been working on applying geometry processing to 3D printing. He has worked with UT’s Institute for Computational Engineering and Sciences to investigate designing 3D-printed mechanical objects, such as an analog clock, that actually work. Uncertainty from the process of 3D printing, even under the best circumstances, creates challenges when printing complex objects.

“You’re never quite sure what you’re going to get out of the 3D printer,” Vouga said. “Small variations can cause large changes in the behavior of the object you’re trying to build. If your gear is slightly too bumpy or if it’s slightly too fat, it won’t turn anymore (because) there will be too much friction between the gears.”

In order to compensate for these effects, the researchers are working on algorithms that make it less likely that the resulting objects will not fit together. The algorithms must understand the design and the function of the object, then use this information to predict any errors the 3D printer will make and adjust the shape of the object that will be printed.

His most recent research, published last October, explores reverse-engineering and mimicking the growth of complicated-looking biological objects, such as leaves and flowers, from simple shapes. Since 3D printers can’t print thin objects accurately, the researchers came up with a technique using the mathematics of biological growth to create a 3D object out of two dimensions using plastics that swell or shrink at different rates when heated. This could lead to objects that change shape in response to surrounding conditions and robotics that can move without motors.

Just like finding the best shape for a building, both of these problems rely on understanding and optimizing the geometry of a needed shape. Vouga said these solutions will start to let 3D printing overcome its limitations and live up to some of people’s expectations.

“They tell you that you’ll be able to 3D-print anything that you want at home and you won’t ever need to go to the store again,” he said. “This is nonsense, there’s only a certain amount of practical objects that you can actually 3D-print.”

Vouga said that understanding geometry is important to comprehending and recreating the behavior of important processes, such as leaf growth and building stability.

“Although these sound like very different questions about very different topics, at the heart of all of these is the relationship between geometry and function,” he said. “If we can understand geometry, and compute with it, we can better understand and predict the physics of the natural world.”

On Sat, 9 Nov 2019, the UT Programming Team won the International Collegiate Programming Contest (ICPC) South Central USA Regional Competition at Baylor University in Waco, Texas. The winning team, consisting of Aditya Durvasula ('19), Aaron Lamoreaux ('23), and Viraj Maddur ('23), will compete in the ICPC World Finals this coming June in Moscow, Russia.

The competition consisted of 60 teams from 25+ schools (approximately 180 students) from across Texas, Louisiana, and Oklahoma. UT Austin's top team solved 12 of the 12 problems. UT Austin's other three teams came in 3rd (Aditya Arjun, Kevin Li, Luke Gretta), 4th (Jake Crouch, James Dong, Kevin Chen), and 6th (Alex Hong, Davis Robertson, Tres Brenan).

UT has been competing in the regionals since 1997. This is UT's fourth consecutive win. UT went to the 2016 world finals in South Dakota, the 2017 world finals in Beijing, and the 2018 world finals in Portugal. UT has seen marked improvement since the creation of a new elective, CS104c: Competitive Programming, taught by the faculty coaches Etienne Vouga and Glenn Downing, in conjunction with the student officers of the UT Programming Contest.

The ICPC traces its roots to 1970 when the first competition was hosted by pioneers of the Alpha Chapter of the UPE Computer Science Honor Society. The initiative spread quickly within the United States and Canada as an innovative program to raise increase ambition, problem-solving aptitude, and opportunities of the strongest students in the field of computing. Over time, the contest evolved into a multi-tier competition with the first championship round conducted in 1977. Since then, the contest has expanded into a worldwide collaborative of universities hosting regional competitions that advance teams to the annual global championship round, the ICPC World Finals.

The International Collegiate Programming Contest is the premier global programming competition conducted by and for the world’s universities. The ICPC is affiliated with the ICPC Foundation and is headquartered at Baylor University. The contest fosters creativity, teamwork, and innovation in building new software programs, and enables students to test their ability to perform under pressure. The contest has raised aspirations and performance of generations of the world’s problem solvers in the computing sciences and engineering.

Picture two rigid metal pieces tangled together. What steps would you take to untangle them?

The most straightforward approach involves twisting each wire to line up the gaps and then pulling one through the other. The design of wire puzzles becomes more complex, like the ones below.

At The University of Texas at Austin and McGill University, researchers are examining the geometrical aspects of puzzle creation and resolution. Dr. Xinya Zhang, a recent UT Computer Science doctoral graduate, collaborated with professors Dr. Etienne Vouga from UT Austin's Department of Computer Science and Dr. Paul Kry from McGill University's School of Computer Science. Together, they explored mathematical methodologies and theories in puzzle design, aiming to establish precise criteria for delineating the characteristics of a puzzle.

A large bulk of previous research in puzzles tends to focus on the variability of solutions. However, there is little work designating the criteria for a puzzle’s design. The team chose to investigate wire puzzles because their design makes it possible to perform a geometrical assessment of the puzzle’s qualities and solutions. 

“It was the simplest geometry that could still give us interesting, non-trivial puzzles,” Vouga says. 

Their primary consideration in puzzle selection was the requirement for a challenging experience.

“[If we look at non-puzzles], such as a nut and a bolt. There’s not really much of a choice of what to do. You only screw it back and forth. On the other hand, if you have something like a hook on a ring, there’s lots of flexibility there. It’s also unconstrained,” says Kry.

Flexibility makes the wire puzzle a perfect option to assess a puzzles’ level of challenge, as there are many different ways to move the wires around. The structure of the wire is referred to as a tunnel if it is straight and narrow, and as a curved pipe if it is not. The presence of bubbles, or the areas where the wires are loosely entangled, provides the space for the puzzle-solver to figure out a configuration to separate the wires. The team determined that in order for a wire puzzle to be considered challenging, it must contain curved pipes in its tunnel-bubble structure.

The team also hypothesized this tunnel-bubble structure is effective in discerning puzzles from non-puzzles. Additionally, they noticed that disentanglement puzzles involved twisting moves to entwine segments of the two pieces around each other. The team proposes that absence of twistiness is a strong indicator of a non-puzzle. Since the wires themselves are still rigid, which lends itself to a computational analysis.

To look for the existence of tunnel-bubble structure, the researchers created two quantitative metrics. With each disentanglement puzzle, they computed a solution (using an algorithm created in the team’s previous study). Although the computed paths were not always the most optimal, or efficient, solution, it makes them more realistic since a puzzle is solved if any solution is found. Their approach also takes into account other steps a puzzle-solver may take, like finding a dead end or retracing their steps.

To find the tunnel-bubble, or loops, in structures in the two wires of disentanglement, researchers introduced a metric of visibility volume. Visibility volume looks at how much clearance or area there is before the puzzle-solver collides with another wire. Remember, the point of solving a disentanglement puzzle is to untangle the wires without them touching.

The team ultimately concluded that these features can contribute to an optimization model of a puzzle. Although their model could not comprehensively look at every aspect of a puzzle, it was effective at establishing a set of criteria for their future work. Their next step toward achieving that goal is to look at even more flexible puzzles, such as those with a rope.

“[Those puzzles] make the wire metal puzzles look easy, because their rigid objects. The algorithm would be much more challenging to compute,” Kry says.

With each puzzle they study, the team continues to examine components of their structure that make the puzzle challenging and enjoyable to its users. Ultimately, the team’s goal is to utilize this criteria to come up with their own unique design.

This past month, UTPC competed at the International Collegiate Programming Contest (ICPC) World Finals hosted by the Arab Academy for Science, Technology and Maritime Transport in Luxor, Egypt.

The competition consisted of teams from 124 regions (approx. 372 students) trying to solve 11 problems in 5 hrs. The first-place team, Peking University, solved 10 problems. The second-place team, M.I.T., solved 9 problems.

UT solved 6 problems and came in 53rd place, 9th place in North America.

Teams consist of three students. The students on the UTPC team were Jiawei Li (current Ph.D.), Ruoshi Dai ('23, M.S.), and Stanley Wei ('23, Turing Scholar). The faculty coaches were Professor Etienne Vouga and Professor Glenn Downing.

In addition, Prof. Vouga and Prof. Downing were awarded The ICPC Foundation Coaching Award for excellence in coaching, having advanced to the ICPC World Finals for 5 or more years.

UT has been competing since 1997. UT went to the 2016-17 World Finals in South Dakota, the 2017-18 World Finals in Beijing, the 2018-19 World Finals in Portugal, and the 2019-20 World Finals in Moscow.

UT has seen marked improvement since creating a new elective, CS104c: Competitive Programming in 2014, taught by Prof. Vouga and Prof. Downing and the student officers of the UT Programming Club.

The ICPC traced its roots to 1970 when pioneers of the Alpha Chapter of the UPE Computer Science Honor Society hosted the first competition. The initiative spread quickly within the United States and Canada as an innovative program to increase students' ambition, problem-solving aptitude, and opportunities in computing.

Over time, the contest evolved into a multi-tier competition, with the first championship round conducted in 1977. Since then, the tournament has expanded into a worldwide collaboration of universities hosting regional competitions that advance teams to the annual global championship, the ICPC World Finals.
The International Collegiate Programming Contest (ICPC) is the premier global programming competition conducted by and for the world's universities. The ICPC is part of the ICPC Foundation.

The contest fosters creativity, teamwork, and innovation in building new software programs and enables students to test their ability to perform under pressure. The tournament has raised the aspirations and performance of generations of the world's problem solvers in the computing sciences and engineering.

Article written by Prof. Glenn Downing