Month: November 2017

What is Ethereum?

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With all the hype going around Blockchain and it’s infrastructure users like Bitcoin and Ethereum are all over the media and magazines I had to write a blog on Ethereum. Briefly, Blockchain is to Bitcoin, what the internet is to email. A big electronic system, on top of which you can build applications.

Then what’s Ethereum? It is a public database that keeps a permanent record of digital transactions. Importantly, this database doesn’t require any central authority to maintain and secure it.

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Like Bitcoin, Ethereum is a distributed public blockchain network. Although there are some significant technical differences between the two, the most important distinction to note is that Bitcoin and Ethereum differ substantially in purpose and capability. Bitcoin offers one particular application of blockchain technology, a peer to peer electronic cash system that enables online Bitcoin payments. While the Bitcoin blockchain is used to track ownership of digital currency (bitcoins), the Ethereum blockchain focuses on running the programming code of any decentralized application.

In the Ethereum blockchain, instead of mining for bitcoin, miners work to earn Ether, a type of crypto token that fuels the network. Beyond a tradeable cryptocurrency, Ether is also used by application developers to pay for transaction fees and services on the Ethereum network.

The Ethereum blockchain is essentially a transaction-based state machine, which means that on a series of specific inputs, it will transition to a new state. The first state in Ethereum is the genesis state, which means a blank state, wherein no transactions have happened on the network. After a transaction occurs, the genesis state transitions to a new state, possibly a final state denoting the current state of Ethereum. Of course, there are millions of transactions occurring concurrently, whereby these transactions are grouped in Blocks. So to simplify, a Block contains a series of transactions.

To cause a transition from one state to the next, a transaction must be valid. For a transaction to be considered valid, it must go through a validation process known as mining. Mining is when a group of nodes (i.e. computers) expend their compute resources to create a block of valid transactions. In the most basic sense, a transaction is a cryptographically signed piece of instruction that is generated by an externally owned account, serialized, and then submitted to the blockchain.

Any node on the network that declares itself as a miner can attempt to create and validate a block. Lots of miners from around the world try to create and validate blocks at the same time. Each miner provides a mathematical “proof” when submitting a block to the blockchain, and this proof acts as a guarantee: if the proof exists, the block must be valid.

For a block to be added to the main blockchain, the miner must prove it faster than any other competitor miner. The process of validating each block by having a miner provide a mathematical proof is known as a “proof of work.”

A miner who validates a new block is rewarded with a certain amount of value for doing this work. What is that value? The Ethereum blockchain uses an intrinsic digital token called “Ether.” The value token of the Ethereum blockchain is called ether. It is listed under the code ETH and traded on cryptocurrency exchanges. It is also used to pay for transaction fees and computational services on the Ethereum network. Every time a miner proves a block, new Ether tokens are generated and awarded. Ether can be transferred between accounts and used to compensate participant nodes for computations performed.

EVM – Ehtereum Virtual Machine

Ethereum is a programmable blockchain. Rather than give users a set of pre-defined operations (e.g. bitcoin transactions), Ethereum allows users to create their own operations of any complexity they wish. In this way, it serves as a platform for many different types of decentralized blockchain applications, including but not limited to cryptocurrencies.

Ethereum in the narrow sense refers to a suite of protocols that define a platform for decentralized applications. At the heart of it is the Ethereum Virtual Machine (“EVM”), which can execute code of arbitrary algorithmic complexity. In computer science terms, Ethereum is “Turing complete”. Developers can create applications that run on the EVM using friendly programming languages modeled on existing languages like JavaScript and Python.

Smart Contracts

Smart contracts are deterministic exchange mechanisms controlled by digital means that can carry out the direct transaction of value between untrusted agents. They can be used to facilitate, verify, and enforce the negotiation or performance of economically-laden procedural instructions and potentially circumvent censorship, collusion, and counter-party risk. In Ethereum, smart contracts are treated as autonomous scripts or stateful decentralized applications that are stored in the Ethereum blockchain for later execution by the EVM. Instructions embedded in Ethereum contracts are paid for in ether (or more technically “gas”) and can be implemented in a variety of Turing complete scripting languages.

There’s still a lot more to Ethereum, but this blog will help you get some insights before delving in deeper in the utopian world of blockchain and cryptocurrency.

 

(sources: Wiki, Telegraph, Medium, ethdocs)

Quantum Network

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We all know the hype that’s currently running around Quantum Computer, their working and a plethora of discoveries happening in Quantum Computing. Recommended: Quantum Computing, Quantum Computer Memories.

Recently, there has been news about a Quantum Network or rather, Quantum Internet. So what’s Quantum Network? Quantum networks form an important element of quantum computing and quantum communication systems. In general, quantum networks allow for the transmission of quantum information (quantum bits, also called qubits), between physically separated quantum processors. A quantum processor is a small quantum computer being able to perform quantum logic gates on a certain number of qubits.

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Being able to send qubits from one quantum processor to another allows them to be connected to form a quantum computing cluster. This is often referred to as networked quantum computing or distributed quantum computing. Here, several less powerful quantum processors are connected together by a quantum network to form one much more powerful quantum computer. This is analogous to connecting several classical computers to form a computer cluster in classical computing. Networked quantum computing offers a path towards scalability for quantum computers since more and more quantum processors can naturally be added over time to increase the overall quantum computing capabilities. In networked quantum computing, the individual quantum processors are typically separated only by short distances.

Going back a year, Chinese physicists launched the world’s first quantum satellite. Unlike the dishes that deliver your Television shows, this 1,400-pound behemoth doesn’t beam radio waves. Instead, the physicists designed it to send and receive bits of information encoded in delicate photons of infrared light. It’s a test of a budding technology known as quantum communications, which experts say could be far more secure than any existing info relay system. If quantum communications were like mailing a letter, entangled photons are kind of like the envelope: They carry the message and keep it secure. Jian-Wei Pan of the University of Science and Technology of China, who leads the research on the satellite, has said that he wants to launch more quantum satellites in the next five years.

The basic structure of a quantum network and more generally a quantum internet is analogous to classical networks. First, we have end nodes on which applications can ultimately be run. These end nodes are quantum processors of at least one qubit. Some applications of a quantum internet require quantum processors of several qubits as well as a quantum memory at the end nodes.

Second, to transport qubits from one node to another, we need communication lines. For the purpose of quantum communication, standard telecom fibers can be used. For networked quantum computing, in which quantum processors are linked at short distances, one typically employs different wavelength depending on the exact hardware platform of the quantum processor.

Third, to make maximum use of communication infrastructure, one requires optical switches capable of delivering qubits to the intended quantum processor. These switches need to preserve quantum coherence, which makes them more challenging to realize than standard optical switches.

Finally, to transport qubits over long distances one requires a quantum repeater. Since qubits cannot be copied, classical signal amplification is not possible and a quantum repeater works in a fundamentally different way than a classical repeater.

The quantum internet could also be useful for potential quantum computing schemes, says Fu. Companies like Google and IBM are developing quantum computers to execute specific algorithms faster than any existing computer. Instead of selling people personal quantum computers, they’ve proposed putting their quantum computer in the cloud, where users would log into the quantum computer via the internet. While running their computations, they might want to transmit quantum-encrypted information between their personal computer and the cloud-based quantum computer. “Users might not want to send their information classically, where it could eavesdrop,” Fu says. But still, this technology is almost 13 years away and surely we will witness a lot more discoveries in the coming years.

(source : MitTechReview, Wikipedia, Wired)

 

 

CNN vs DCGAN

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DCGANs stand for Deep Convolutional Generative Adversarial Networks. It is quite the contrary to a Convolutional Neural Network (CNN). It works in an opposite direction compared to a CNN. What CNN does is that it transforms an image to class labels, that is a list of probabilities, whereas DCGAN generates an image from random parameters.

CNNs and DCGANs

 

Some of you might wonder what are convolutions. Convolutions are the operations or the modifications we perform on an image. We perform modifications on the image kernel by multiplying it with the matrix of the operation we want to perform. For detailed information on image kernel and convolutions please visit here.

Moving on, what CNN does is it applies a lot of filters to extract various features from a single image. CNN applies multi-layered filters to a single image to extract features moving deeper into the layers.

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Now the typical working on CNNs is that it starts from a single RGB image on the right, multiple filtering layers are applied to produce smaller and large number of images.

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Flow of CNNs

 

Image generation flow of DCGANs

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Flow of DCGANs

 

Now, the filters that we previously mentioned are convolutional in CNNs and transposed-convolutional in DCGANs, both of them work in the opposite direction.

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Illustration of their working

Convolution: (Bottom Up) 3×3 blue pixels contribute to generating a single green pixel. Each of 3×3 blue pixels multiplied by the corresponding filter value, and the results from different blue pixels summed up to be a single green pixel.

Transposed-Convolutions: (Top Down) A single green pixel contributes to generating 3×3 blue pixels. Each green pixel is multiplied by each 3×3 filter values and the results from different green pixels are summed up to be a single blue pixel.

 

It is suggested that the input parameters could use a semantic structure as in the following example-

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Interpretation of Input Parameters

 

Training Strategies:

CNN: Classifying authentic and fake images. Here, authentic images are provided as training data to the model.

DCGAN: It is trained to generate images classified as authentic by the CNN. It works by trying to fool the CNN, DCGAN learns to generate images similar to the training data.