# Colloquia and Seminars

To join the email distribution list of the cs colloquia, please visit the list subscription page.Computer Science events calendar in HTTP ICS format for of Google calendars, and for Outlook.

Academic Calendar at Technion site.

- Bioinformatics Forum
- BizTEC Forum
- ceClub
- CGGC Weekly Seminar
- Coding Theory Seminar
- Colloquia
- Haifux, Haifa Linux Club
- Pixel Club
- Theory Seminar

## Upcoming Colloquia & Seminars

### Intel@Technion Lectures: Game Changing Design

- Speaker:
- Shlomit Weiss (Intel)
- Date:
- Wednesday, 1.6.2016, 11:30
- Place:
- Room 337-8 Taub Bld.

produce design developed in through the years in many fronts and requirements. Today SOC products require aggressive targets in all fronts: frequency, performance, low cost, low power…… To address those new and growing requirement there needs to be a basic change in the design concept and solutions. Working in parallel convergence, parallel fronts and analyze tradeoffs together is the approach used to being the best SOC products to the market. This talk is describing the challenge and principals in applying the new approach.

Short bio:

Shlomit Weiss, VP Data Center Group – General Manager Silicon Development Networking Group, Intel. In her previous role Shlomit was GM of Client Products Development responsible design of all Client SOC products. In her role managed a cross site organization of about 650 people. Between the products designed and developed in the organization 6th generation “Core names Best processor Ever”. She is based in Intel Israel, has been at Intel since 1989, with a third of her time in different positions in the US. In her career at Intel Weiss has worked in various projects starting in validation, design, cluster manager, and architecture. Previously Weiss managed the architecture of the Intel® Core™ 2 Duo processor definition receiving an Intel Achievement Award, one of most prestigious Intel awards, for the architecture of that CPU. Weiss earned her master's degree cum laude in computer engineering from Technion in Haifa, Israel. In her limited free time, Shlomit enjoys traveling, folk dancing and spending time with her family.### Theory Seminar: Two Applications of Communication Complexity in Distributed Computing

- Speaker:
- Rotem Oshman (Tel-Aviv University)
- Date:
- Wednesday, 1.6.2016, 12:30
- Place:
- Taub 201

In distributed systems, communication between the participants in the computation is usually the most expensive part of the computation. Theoretical models of distributed systems usually reflect this by neglecting the cost of local computation, and charging only for messages sent between the participants; in particular, we usually assume that the computation proceeds in rounds, and in each round each participant can send only a limited number of bits. We are interested in characterizing the number of rounds required to perform various tasks.

In this talk I will describe two sets of results. The first concerns the complexity of distributed subgraph detection: we have n servers, each representing a node in an undirected graph, and each server receives as input its adjacent edges in the graph. The goal of the computation is to determine whether the global input graph contains some fixed subgraph. I will describe upper and lower bounds for several classes of subgraphs, through a connection to Turan numbers. The general case remains open.

In the second part of the talk I will describe recent work on multi-party number-in-hand communication and information complexity, and show a tight upper and lower bound for set disjointness in the shared blackboard model.

Joint work with Mark Braverman, Andrew Drucker and Fabian Kuhn.### Sidecore Managment for Virtualized Environments

- Speaker:
- Eyal Moscovici, M.Sc. Thesis Seminar
- Date:
- Wednesday, 1.6.2016, 12:30
- Place:
- Taub 601
- Advisor:
- Prof. D. Tsafrir

Virtualization is the ability of modern computer systems to run guest Virtual Machines (VMs). The VM host exposes various I/O devices to its guests such as the Network Interface Controller (NIC), hard disk, etc. Para-virtual I/O is a common technique for presenting the guest VM with an interface similar, but not identical, to the underlying hardware. Such interfaces are called virtual I/O devices, and their behavior is emulated by the VM host. This emulation must be scalable, must be able to handle high throughput I/O workloads, and must not consume system resources during periods of low throughput. Today there are two leading approaches: traditional paravirtual I/O and sidecores. In the traditional approach VM guests experience performance degradation while handling high-throughput I/O workloads. On the other hand, the sidecore approach always consumes a set amount of system re- sources which are wasted during low-throughput I/O workloads. This work explores a dynamic virtual I/O device management design that improves system utilization by combining the two. We present SidecoreM which uses an I/O manager to dynamically deter- mine the preferred approach based on the current I/O load. To this end we first modeled the system under varying I/O workloads, then implemented the I/O manager based on the model. Evaluation of our design under Linux shows that SidecoreM is able to find the optimum configuration in all cases tested but one. While searching for the optimum configuration we degrade performance by at most 6% com- pared to a statically tuned system. SidecoreM shows up to 2.2x performance gain over the traditional approach. SidecoreM incurs 280us of overhead per second during normal operation, and a few milliseconds when changing the configuration of the system.

### On Routing schemes that are robust to changes in bandwidth demand

- Speaker:
- Gal Cohen, M.Sc. Thesis Seminar
- Date:
- Sunday, 5.6.2016, 10:00
- Place:
- Taub 601
- Advisor:
- Prof. D. Raz

A major challenge in optimizing network utilization is how to reduce bottleneck links, while taking into account that bandwidth demands may be increased over time. Traffic engineering algorithms attempt to address this challenge by employing smart routing, however current solutions optimization criterion is biased towards a non-realistic setting in which demands are increased uniformly. In this talk, I will present a novel traffic engineering algorithm which is the first to consider the more realistic assumption, that only some (unknown) set of demands will increase. An exact solution to this problem is exponential in the initial number of demands, however we show that some of the constraints can be omitted without affecting the solution, thereby easing the computation complexity. We use this observation to design an algorithm that takes a network and bandwidth demands and returns a routing robust to non-uniform demand increase. We evaluated our algorithm on two network graphs and compared against previous work. Experimental results indicate that our algorithm outperforms the most widely used algorithm by up to 10%.

### 2D Simulation and Mapping using the Cauchy-Green Complex Barycentric Coordinates

- Speaker:
- Aviv Segall, M.Sc. Thesis Seminar
- Date:
- Sunday, 5.6.2016, 13:30
- Place:
- Taub 401
- Advisor:
- Prof. Mirela Ben-Chen

Conformal maps are especially useful in geometry processing for computing shape preserving deformations, image warping and manipulating harmonic functions. The Cauchy-Green coordinates are complex-valued barycentric coordinates, which can be used to parameterize a space of conformal maps from a planar domain bounded by a simple polygon. In this work, we use the Cauchy-Green coordinates to simulate 2D potential flow with interactive control, and to construct conformal maps between planar domains. The Hele-Shaw flow describes the slow flow of a viscous liquid between two parallel plates separated by a small gap. In some configurations such a flow generates instabilities known as Saffman-Taylor fingers, yielding intricate visual patterns which have been an inspiration for artists, yet are quite difficult to simulate efficiently. Formulating the equations with our framework allows us to efficiently simulate the flow and to provide the user with interactive control over the behavior of the fingers. Additionally, we show that the Cauchy-Green coordinates are applicable to the exterior of the domain, and use them for simulating two fluids with different viscosities. The Riemann mapping theorem guarantees that there exists a conformal map between any two simply connected planar domains, yet computing this map efficiently is challenging. One of the main challenges is finding the boundary correspondence between the two domains. We use the Cauchy-Green coordinates for parameterizing the space of conformal maps from the source domain, and propose an alternating minimization algorithm for constructing a boundary-approximating conformal map, which implicitly finds a boundary correspondence. We enrich the space of solutions by generalizing the setup to quasi-conformal maps, and allow the user to interactively control the result using point-to-point and stroke-to-stroke constraints. Finally, we show applications to stroke based deformation and constrained texture mapping.

### CGGC Seminar: 2D Simulation and Mapping using the Cauchy-Green Complex Barycentric Coordinates

- Speaker:
- Aviv Segall (CS, Technion)
- Date:
- Sunday, 5.6.2016, 13:30
- Place:
- Taub 401

Conformal maps are especially useful in geometry processing for computing shape preserving deformations, image warping and manipulating harmonic functions. The Cauchy-Green coordinates are complex-valued barycentric coordinates, which can be used to parameterize a space of conformal maps from a planar domain bounded by a simple polygon. In this work, we use the Cauchy-Green coordinates to simulate 2D potential flow with interactive control, and to construct conformal maps between planar domains.

The Hele-Shaw flow describes the slow flow of a viscous liquid between two parallel plates separated by a small gap. In some configurations such a flow generates instabilities known as Saffman-Taylor fingers, yielding intricate visual patterns which have been an inspiration for artists, yet are quite difficult to simulate efficiently. Formulating the equations with our framework allows us to efficiently simulate the flow and to provide the user with interactive control over the behavior of the fingers. Additionally, we show that the Cauchy-Green coordinates are applicable to the exterior of the domain, and use them for simulating two fluids with different viscosities.

The Riemann mapping theorem guarantees that there exists a conformal map between any two simply connected planar domains, yet computing this map efficiently is challenging. One of the main challenges is finding the boundary correspondence between the two domains. We use the Cauchy-Green coordinates for parameterizing the space of conformal maps from the source domain, and propose an alternating minimization algorithm for constructing a boundary-approximating conformal map, which implicitly finds a boundary correspondence. We enrich the space of solutions by generalizing the setup to quasi-conformal maps, and allow the user to interactively control the result using point-to-point and stroke-to-stroke constraints. Finally, we show applications to stroke based deformation and constrained texture mapping.### Pixel Club: Three Dimensional Structure Determination of macro-Molecules in Cryo-electron Microscopy

- Speaker:
- Gabi Pragier (Tel-Aviv University)
- Date:
- Tuesday, 7.6.2016, 11:30
- Place:
- EE Meyer Building 1061

One of the primary challenges in single particle reconstruction in cryo-electron microscopy is to find the three-dimensional structure of a molecule using its two-dimensional noisy projection-images. We suggest a method to estimate the unknown imaging orientations of all projection-images that is independent of their distribution. Since the relative orientation between each pair of images may only be estimated up to a two-way handedness ambiguity, we suggest an efficient procedure to remove these ambiguities by casting the problem as a graph-partitioning problem. In addition, we present an algorithm for determining the three-dimensional structure of molecules that have a 4-way rotational symmetry. Our algorithm is based on self-common-lines whose location is related to the tilt angle of the underlying image's viewing-direction. These lines admit quite a few favorable geometrical constraints, thus enabling their detection even in extremely noisy settings.

We demonstrate the efficacy of our approach using simulated clean and noisy data.### CGGC Seminar: A B-spline based Framework for Volumetric Object Modeling

- Speaker:
- Fady Massarwi (CS, Technion)
- Date:
- Monday, 13.6.2016, 14:00
- Place:
- Room 337-8 Taub Bld.

This work extends a recently proposed robust computational framework for constructing the boundary representation (B-rep) of the volume swept by a given smooth solid moving along a one parameter family h of rigid motions. Our extension allows the input solid to have sharp features, and thus it is a significant and useful generalization of that work. This naturally requires a precise description of the geometry of the surface generated by the sweep of a sharp edge supported by two intersecting smooth faces. We uncover the geometry along with the related issues like parametrization and singularities via a novel mathematical analysis. Correct trimming of such a surface is achieved by an analysis of the interplay between the cone of normals at a sharp point and its trajectory under h. The overall topology is explained by a key lifting theorem which allows us to compute the adjacency relations amongst entities in the swept volume by relating them to corresponding adjacencies in the input solid. Moreover, global issues related to body-check such as orientation, singularities and self-intersections are efficiently resolved. Examples from a pilot implementation illustrate the efficiency and effectiveness of our framework.

This work is jointly done with Prof. Milind Sohoni and Prof. Bharat Adsul at IIT Bombay, India.### CGGC Seminar:Incorporating Sharp Features in the General Solid Sweep Framework

- Speaker:
- Jinesh Machchhar (CS, Technion)
- Date:
- Monday, 13.6.2016, 14:30
- Place:
- Room 337-8 Taub Bld.

This work extends a recently proposed robust computational framework for constructing the boundary representation (B-rep) of the volume swept by a given smooth solid moving along a one parameter family h of rigid motions. Our extension allows the input solid to have sharp features, and thus it is a significant and useful generalization of that work. This naturally requires a precise description of the geometry of the surface generated by the sweep of a sharp edge supported by two intersecting smooth faces. We uncover the geometry along with the related issues like parametrization and singularities via a novel mathematical analysis. Correct trimming of such a surface is achieved by an analysis of the interplay between the cone of normals at a sharp point and its trajectory under h. The overall topology is explained by a key lifting theorem which allows us to compute the adjacency relations amongst entities in the swept volume by relating them to corresponding adjacencies in the input solid. Moreover, global issues related to body-check such as orientation, singularities and self-intersections are efficiently resolved. Examples from a pilot implementation illustrate the efficiency and effectiveness of our framework.

This work is jointly done with Prof. Milind Sohoni and Prof. Bharat Adsul at IIT Bombay, India.### Understanding Word Embeddings

- Speaker:
- Omer Levy - CS-Lecture -
- Date:
- Thursday, 16.6.2016, 15:00
- Place:
- Room 337-8 Taub Bld.
- Link:
- http://www.cs.technion.ac.il/~colloq/20160616_15_00_Levy.html