Huffman Encoding using VLSI

Huffman coding is entropy encoding algorithm used for lossless data compression. It basically uses variable length coding which is done using binary tree method. In our implementation of Huffman encoder, more frequent input data is encoded with less number of binary bits than the data with less frequency.This way of coding is used in JPEG and MPEG for image compression. Huffman coding uses a specific method for choosing the representation for each symbol, resulting in a prefix code. Prefix-free codes means the bit string representing some particular symbol is never a prefix of the bit string representing any other symbol

EXPLANATION OF THE ALGORITHMS FOR DISPLAYING 3D FIGURES ON THE COMPUTER SCREEN

Not long time ago people can only dream about the thing that they can see 3-dimensional world inside of the screen of the computer. Computers at that time can display only 256 colors on their screens, they can work only with integer numbers, and their computation speed was not fast enough. This dream comes true with the help of Id Software company. This company started to build its games by using of simplified 3D graphics. All these simplified 3D graphics were calculated by the software 3D rendering algorithms which were not published by these company. At that time there was a global goal to speedup calculations for 3D graphics and to make it look more realistic. The solution for this comes from hardware companies. Hardware companies started to work on hardware 3D accelerators, which can render 3D graphics much faster than software algorithms. These 3D accelerators are fully patented, so that no one knows how they are implemented inside. At that time there were proposed two 3D rendering interfaces: Direct3D and OpenGL. And manufacturers of graphic cards started supporting both of these interfaces. Lots of game development companies started to use these interfaces. And also Id Software company started to redesign its game engine to support these interfaces to take place in game market. From that time, everybody started to use 3D accelerators with built-in 3D rendering features and as a result everybody forgot about software 3D rendering algorithms. Nowadays the situation come in the following way, that most of the algorithms which are used in 3D games are not published on paper, and all the 3D accelerator internal algorithms are patented. All modern 3D graphics are fully conserved by the video cards, so that 3D rendering could not be developed in other way. The goal of this article is explanation of how 3D graphics can be displayed on the screen of the computer

On the Cost of Transitive Closures in Relational Databases

We consider the question of taking transitive closures on top of pure relational systems (Sybase and Ingres in this case). We developed three kinds of transitive closure programs, one using a stored procedure to simulate a built-in transitive closure operator, one using the C language embedded with SQL statements to simulate the iterated execution of the transitive closure operation, and one using Floyd's matrix algorithm to compute the transitive closure of an input graph. By comparing and analyzing the respective performances of their different versions in terms of elapsed time spent on taking the transitive closure, we identify some of the bottlenecks that arise when defining the transitive closure operator on top of existing relational systems. The main purpose of the work is to estimate the costs of taking transitive closures on top of relational systems, isolate the different cost factors (such as logging, network transmission cost, etc.), and identify some necessary enhancements to existing relational systems in order to support transitive closure operation efficiently. We argue that relational databases should be augmented with efficient transitive closure operators if such queries are made frequently

A NOTE ON HARDNESS OF MULTIPROCESSOR SCHEDULING WITH SCHEDULING SOLUTION SPACE TREE

We study the computational complexity of the non-preemptive scheduling problem of a listof independent jobs on a set of identical parallel processors with a makespan minimizationobjective. We make a maiden attempt to explore the combinatorial structure showing theexhaustive solution space of the problem by defining the Scheduling Solution Space Tree(SSST) data structure. The properties of the SSST are formally defined and characterizedthrough our analytical results. We develop a unique technique to show the problemNP using the SSST and the Weighted Scheduling Solution Space Tree (WSSST) datastructures. We design the first non-deterministic polynomial-time algorithm named MagicScheduling (MS) for the problem based on the reduction framework. We also define anew variant of multiprocessor scheduling by including the user as an additional inputparameter. We formally establish the complexity class of the variant by the reductionprinciple. Finally, we conclude the article by exploring several interesting open problemsfor future research investigation