The WCET Tool Challenge 2011

2012

Model checking with program slicing has been successfully applied to compute Worst Case Execution Time (WCET) of a program running in a given hardware. This method lacks path feasibility analysis and suffers from the following problems: The model checker (MC) explores exponential number of program paths irrespective of their feasibility. This limits the scalability of this method to multiple path programs. And the witness trace returned by the MC corresponding to WCET may not be feasible (executable). This may result in a solution which is not tight i.e., it overestimates the actual WCET. This thesis complements the above method with path feasibility analysis and addresses these problems. To achieve this: we first validate the witness trace returned by the MC and generate test data if it is executable. For this we generate constraints over a trace and solve a constraint satisfaction problem. Experiment shows that 33% of these traces (obtained while computing WCET on standard WCET benchmark programs) are infeasible. Second, we use constraint solving technique to compute approximate WCET solely based on the program (without taking into account the hardware characteristics), and suggest some feasible and probable worst case paths which can produce WCET. Each of these paths forms an input to the MC. The more precise WCET then can be computed on these paths using the above method. The maximum of all these is the WCET. In addition this, we provide a mechanism to compute an upper bound of over approximation for WCET computed using model checking method. This effort of combining constraint solving technique with model checking takes advantages of their strengths and makes WCET computation scalable and amenable to hardware changes. We use our technique to compute WCET on standard benchmark programs from Mälardalen University and compare our results with results from model checking method.

ACM SIGCSE Bulletin, 1985

Below are reproduced the 7 problems presented by the Contest Judges to team s competing in the 9th ACM Scholastic Programming Contest held in New Orleans, LA, on Marc h 15, 1985. This article represents the third annual publication of the Contest problems i n the SIGCSE Bulletin. It is hoped that this publication will be helpful to those involve d either in programming contest administration or competition. It may also be of interes t to computer science educators who are often searching for new challenges to pose to thei r students. The contest was under the overall direction of Gary Ford of the University o f Colorado at Colorado Springs .

Gyankosh Prokashoni, 2006

I am happy to be able to introduce the 2nd Edition of this book to the readers. The objective of this edition is not only to assist the contestants during the contest hours but also describing the core subjects of Computer Science such as C Programming, Data Structures and Algorithms. This edition is an improvement to the previous edition. Few more programming techniques like STL (Standard Template Library), manipulating strings and handling mathematical functions are introduced here.

Computers & Operations Research, 2012

How to assign colors to occurrences of cars in a car factory ? How to divide fairly a necklace between thieves who have stolen it ? These two questions are addressed in two combinatorial problems that have attracted attention from a theoretical point of view these last years, the first one more by people from the combinatorial optimization community, the second more from the topological combinatorics and computer science point of view. The first problem is the paint shop problem, defined by Epping, Hochstättler and Oertel in 2004. Given a sequence of cars where repetition can occur, and for each car a multiset of colors where the sum of the multiplicities is equal to the number of repetitions of the car in the sequence, decide the color to be applied for each occurrence of each car so that each color occurs with the multiplicity that has been assigned. The goal is to minimize the number of color changes in the sequence. The second problem, highly related to the first one, takes its origin in a famous theorem found by Alon in 1987 stating that a necklace with t types of beads and qau occurrences of each type u (au is a positive integer) can always be fairly split between q thieves with at most t(q − 1) cuts. An intriguing aspect of this theorem lies in the fact that its classical proof is completely nonconstructive. Designing an algorithm that computes theses cuts is not an easy task, and remains mostly open. The main purpose of the present paper is to make a step in a more operational direction for these two problems by discussing practical ways to compute solutions for instances of various sizes. Moreover, it starts with an exhaustive survey on the algorithmic aspects of them, and some new results are proved.

1991

The deadline for this coursework is NOON on Thursday 25th November, 2010. Please submit your solutions electronically via submit. This is worth 50% of the coursework for A&DS. In this coursework, we consider the "knapsack counting" problem. Your mission is to understand, implement, and experiment with a suite of algorithms for this problem. In the knapsack counting problem, we are given as input a list of non-negative integer weights w 1 , w 2 ,. .. , w n ∈ N, and an upper bound B ∈ N. We say that some specific set S ⊆ {1,. .. , n} represents a feasible knapsack solution (wrt w 1 ,. .. , w n , B) if and only if i∈S w i ≤ B. The total number of feasible knapsack solutions (which we wish to count) is count(n, B) = S ⊆ {1, 2,. .. , n} : i∈S w i ≤ B. Note we may assume wlog that w i ≤ B for all 1 ≤ i ≤ n (we can delete any w i > B). §1 describes how to compute count(n, B) exactly via a recursive (exponential-time) algorithm. §2 describes a dynamic programming which computes count(n, B) exactly in Θ(nB) time. §3 introduces a very basic approximation algorithm, which runs in Θ(n 3) time on a "rounded" version of the input, and returns an "approximate count" within a factor of (n + 1) of count(n, B) (this is an n-approximation algorithm). §3 then shows we can improve the quality of this approximation (to within a factor of 1.25, say, or closer), by drawing uniform samples from the feasible solutions of the "rounded problem", and checking whether or not they also are solutions to the original problem 1. Your task in this coursework is to implement all three algorithms, prove some relevant facts (see §3.1), and write a short report on experimental results.

2021

Automatic maker is meant as a device to produce (or compose) things by itself, by a model, customization or a program. Nowadays the most advanced automatic makers in mass use are 3D-printers.The purpose of the paper is to present methods of generating various Olympiad tasks by using evident images of virtual automatic makers. As a perspective, production (performing) of processes is also considered (as automatic 4D-makers). Besides of the main operation: putting a pixel (voxel), the following primitives with virtual things can be involved: cutting; gluing; putting a building block; erasing a building block; copying a fragment, (for 4D-) shifting a building block. Tasks are generated naturally: to make a given thing (perform a given simple process) optimally in any sense (with respect to time; to number of primitives; to number of building blocks etc.). Such tasks are well-understood, have short formulations and are difficult to be solved even with initial data of small volume; a “br...

The NeverEngine Labs is where Cristian Vogel and Gustav Scholda are developing tools for advanced sound design and composition exclusively for the Kyma sound design environment by Symbolic Sound. The Complexity Lab was launched in July 2015. It ran for one year. We focussed on one of the most powerful areas of Kyma – the algorithmic construction of complex signal flows using Replicators, Scripts and Frames. During one year of sustained research and development, we published over 230 Kyma Sounds, source code and samples ranging from complex noise generators to advanced swarm simulations, only available exclusively to our subscribers. Totalling over 300MB of source samples, code and Kyma examples. In the Complexity Lab, we developed Kyma Sounds which demonstrated the parameterisation and mapping of algorithmically constructed signal flows, exploring how this approach can generate new and exciting sound design techniques. This document is a collection of all the descriptions you will find inline with the custom classes we created, as well as the log file that describes what we published and when, including details about the signal flow examples which are in themselves powerful starting points for your own Kyma development.

Computers & Graphics, 2014

Graphics is a biennial international conference affiliated with the Chinese Computer Federation. It provides a worldwide forum for international researchers, scholars and developers to exchange and explore new ideas and trends on computer-aided design, computer graphics, electronic design automation, and visualization. This venue marked a milestone in the longstanding cooperation between CAD/Graphics and the Computers and Graphics Journal. Unlike previous years, where selected papers would be extended and submitted to special journal sections, the Conference Organizers and the Editor-in-Chief of this journal decided to select all journal-quality papers before the venue, while keeping rigorous standards of excellence. To improve decisions and provide greater quality feedback to authors, this year saw notable changes in the review process. The Program Co-Chairs assigned each paper to a primary reviewer and a secondary reviewer selected from a program committee including world-class experts in the CAD/CG areas. Subsequently the primary invited at least two external reviewers outside the program committee. Each paper received at least three reviews before the primary made a recommendation to the Program Co-Chairs. The Program Co-Chairs made the final decisions based on the primary's recommendations and the assessments of all reviewers. This year the conference received 344 submissions, out of which 31 manuscripts were accepted as regular papers and published in this special section of Computers & Graphics. The selection process took two rounds of reviewing over a period of 9 weeks during which 1159 expert assessments were received. This resulted in a highly competitive acceptance rate of 9.0%. Additionally, 49 full conference papers and 40 poster communications appeared in the conference program and proceedings published by IEEE Conference Publishing Services (CPS). Both journal and conference papers were presented in a two-track format while the posters were discussed in a dedicated session at the conference. This event would not be possible without the enthusiasm and the committed efforts of many dedicated people. We are