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Mathematics of Machine Learning based on Lattice Theory

Reading time7 min
Views2K
Mathematics*Machine learning*

This is a third article in the series of works (see also first one and second one) describing Machine Learning system based on Lattice Theory named 'VKF-system'. It uses structural (lattice theoretic) approach to representing training objects and their fragments considered to be causes of the target property. The system computes these fragments as similarities between some subsets of training objects. There exists the algebraic theory for such representations, called Formal Concept Analysis (FCA). However the system uses randomized algorithms to remove drawbacks of the unrestricted approach. The details follow…
Areas of Formal Concept Analysis

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Machine Learning CPython library 'VKF'

Reading time14 min
Views1.4K
MySQL*Python*Machine learning*
Previous article describes a web server for Machine Learning system 'VKF' based on Lattice Theory. This paper is an attempt to explain details of using the CPython library directly. We reproduce working sessions of experiments on datasets 'Mushroom' and 'Wine Quality' from UCI Machine Learning repository. The structures of input files are discussed too.


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Yii news 2020, issue 5

Reading time4 min
Views1.9K
PHP*Yii*

Hello, community!


It is time for another Yii news issue. Both Yii 2 and Yii 3 are doing well.


I've finally updated the team page on the website to reflect the current state of things.


Konstantin Sirotkin is back and actively taking care of ElasticSearch Yii 2 extension.


Yii 3 main team was formed (actually happened late 2019). Likely you know the names because most were mentioned in previous Yii news issues.


Also, we have partially moved to GitHub actions. Experience is great so far, so we can definitely recommend that. We're adding phan static analysis
and running tests with Infection to make code quality even better.

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Total votes 3: ↑3 and ↓0+3
Comments0

10 Best Email Scraping Tools for Sales Prospecting in 2020

Reading time3 min
Views2.1K
Data Mining*
From sandbox
We all know how hard it is to build an email sales list from scratch, especially for small companies. There left no options due to limited resources. In fact, many companies even buy preset profiled lists from the third party and send identical mass emails. It can put your business in a vulnerable position ascribed into the low quality of the email lists. However, there is a better way to build a highly targeted email list with email scraping tools.

Email scraping can help you collect email addresses shown publicly using a bot. What makes this great is that you have control over where to get the email lists from, and who can opt-in. Moreover, you don’t have to rely on the second-hand source. I profiled a list of best 10 email scraping tools for sales prospecting. Let’s take a look.

1. Zoominfo

A full-featured email scraping platform with a comprehensive database. You can directly search for titles and companies within their platform. It is more like a directory system that covers professionals in all industries with contact information. Email lists are the assets. That said, it comes with a price tag. It is worth to invest if you are looking for accurate sales leads. Zoominfo is an excellent option for enterprise-level sales prospects.

image
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Total votes 3: ↑3 and ↓0+3
Comments0

How to find an English teacher. Part 2

Reading time4 min
Views914
Programming*Machine learning*Data visualization*Python*Natural Language Processing*
image

This is a continuation of story about using Data Science for finding an English teacher. If you have not read it yet - there is an opportunity to become familiar with it

Briefly  -  we had information about language teachers and tried to apply some basic ideas using pandas and our expectations. Unfortunately we got stuck on the third step, because there is not enough information for resolving our the last requirements  -  we need not more 3 candidates at the end.

Disclaimer
It is an approach based on my own experience and can be unsuitable to your point of view, ideas, or principles.
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PVS-Studio is now in Compiler Explorer

Reading time4 min
Views1.1K
PVS-Studio corporate blogProgramming*Compilers*C++*C*
image1.png

Not so long ago, a landmark event has happened: PVS-Studio appeared in Compiler Explorer! Now you can quickly and easily analyze the code for errors right on the godbolt.org site (Compiler Explorer). This feature opens up a large number of new possibilities – from quenching curiosity about the analyzer's abilities to being able to quickly share check results with a friend. This article will cover the topic on how to use these features. Caution – large GIFs!
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Total votes 1: ↑1 and ↓0+1
Comments0

Web server for Machine Learning 'VKF-solver'

Reading time20 min
Views1.6K
Machine learning*MySQL*Python*
Nowadays most people identify Machine Learning with training of various kinds of neural networks. At the beginning there were fully connected networks, then convolutional and recurrent networks replace them, now there exist a quite exotic variants of networks such that GAN and LTSM networks.

Their training requires constantly increasing volume of samples, and they also do not be able to explain why a particular decision was made. Structural approaches to Machine Learning avoiding these drawbacks exist, the software implementation of one of which is described in the article. This is an English translation of original post by the author.


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Total votes 1: ↑1 and ↓0+1
Comments0

How to find an English teacher. Part 1

Reading time5 min
Views1.6K
Data Mining*Data visualization*Natural Language Processing*Programming*Python*


In the modern world, here and there ideas are arising about using data science for an extra benefit. For instance, Google can use a history of watched videos for providing recommendations about new ones. Online shops are using a recommendation system for increasing your receipt. However… if companies use the data for their benefit, could we do the same for own needs such as looking an online English teacher?


Disclaimer

It is an approach based on my own experience and can be unsuitable to your point of view, ideas, or principles.

Total votes 2: ↑1 and ↓10
Comments0

Critical Transcendence: .NET SDK and Apache Spark

Reading time5 min
Views856
.NET*Apache*Microsoft Azure*Microsoft SQL Server*Machine learning*

When Alex Garland’s series Devs (on FX and Hulu) came out this year, it gave developers their own sexy Hollywood workup. Who knew that coders could get snarled into murder plots and love triangles just for designing machine learning programs? Or that their software would cause a philosophical crisis? Sure, the average day of a developer is more code writing than murder but what a thrill to author powerful new program.


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How the PVS-Studio analyzer began to find even more errors in Unity projects

Reading time7 min
Views696
PVS-Studio corporate blogUnity3D*C#*
image1.png

When developing the PVS-Studio static analyzer, we try to develop it in various directions. Thus, our team is working on plugins for the IDE (Visual Studio, Rider), improving integration with CI, and so on. Increasing the efficiency of project analysis under Unity is also one of our priority goals. We believe that static analysis will allow programmers using this game engine to improve the quality of their source code and simplify work on any projects. Therefore, we would like to increase the popularity of PVS-Studio among companies that develop under Unity. One of the first steps in implementing this idea was to write annotations for the methods defined in the engine. This allows a developer to control the correctness of the code related to calls of annotated methods.
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Total votes 3: ↑3 and ↓0+3
Comments0

Making a Tarantool-Based Investment Business Core for Alfa-Bank

Reading time10 min
Views1.9K
VK corporate blogHigh performance*System Analysis and Design*Database Administration*Tarantool*

A still from «Our Secret Universe: The Hidden Life of the Cell»

Investment business is one of the most complex domains in the banking world. It's about not just credits, loans, and deposits — there are also securities, currencies, commodities, derivatives, and all kinds of complex stuff like structured products.

Recently, people have become increasingly aware of their finances. More and more get involved in securities trading. Individual investment accounts have emerged not so long ago. They allow you to trade in securities and get tax credits or avoid taxes at the same time. All clients coming to us want to manage their portfolios and see their reporting on-line. Most frequently, these are multi-product portfolios, which means that people are clients of different business areas.

Moreover, the demands of regulators, both Russian and international, also grow.

To meet the current needs and lay a foundation for future upgrades, we've developed our Tarantool-based investment business core.
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Total votes 14: ↑14 and ↓0+14
Comments0

Meet Hamstand: a smart mobile testing hub

Reading time5 min
Views1.3K
ITMO corporate blogOffices of IT companiesDevelopment of mobile applications*IT systems testing*Mobile applications testing*
The ITMO Accelerator continues to empower entrepreneurs. We’ve already covered some of its most successful graduates — the Laeneco staethoscope and the GoROBO robotics club. Today we’ll be discussing Hamstand — a modular hub that simplifies the process of mobile app testing. Let’s talk about how it came to be, why it’s a welcome addition to many developers’ toolkits, and what awaits the project in the near future.

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Total votes 6: ↑6 and ↓0+6
Comments0

How to introduce a static code analyzer in a legacy project and not to discourage the team

Reading time8 min
Views1.6K
PVS-Studio corporate blogDevOps*Programming*Perfect code*Product Management*


It is easy to try a static code analyzer. But it requires skills to introduce it in the development of an old large project. If the approach is incorrect, the analyzer can add work, slow down development, and demotivate the team. Let's briefly discuss how to properly integrate static analysis into the development process and start using it as part of CI/CD.
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Total votes 1: ↑1 and ↓0+1
Comments0

Monitoring and Logging external services in Kubernetes

Reading time3 min
Views3.3K
DevOps*Kubernetes*
image

Greetings to all!

As a matter of fact I haven't found so far any generalized guide on logging and monitoring of metrics from external systems to Kubernetes on the web. Here I want to share with you my own version. First of all it is supposed that you have already got working Prometheus and other services.

As an example I use third-party data for stateful service RDBMS PostgreSQL in a Docker container. In our company we also use the Helm package manager, and you'll find how it works below. You can see same examples in this article below. You can see same examples in this article below. For a complete solution we create a nested chart.
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Total votes 2: ↑2 and ↓0+2
Comments0

The PVS-Studio analyzer: detecting potential compatibility issues with Java SE API

Reading time9 min
Views707
PVS-Studio corporate blogAPI*Java*Oracle*

Рисунок 9

2019 was a very busy year in terms of conferences. Our team could leave for whole weeks on business trips. As you know, the conference is perfect time to share knowledge. In addition to giving talks and telling many interesting things at our booth, we also learned a lot from communicating with conference participants and speakers. So at the Joker 2019 conference in fall, a talk from Dalia Abo Sheasha «Migrating beyond Java 8» inspired us to implement a new diagnostic rule that allows us to detect incompatibilities in the Java SE API between different versions of Java. This is what we will talk about.
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Total votes 4: ↑4 and ↓0+4
Comments0

The Code of the Command & Conquer Game: Bugs From the 90's. Volume one

Reading time13 min
Views2.1K
PVS-Studio corporate blogC*C++*Open source*Game development*
image1.png

The American company Electronic Arts Inc (EA) has made the source code of the games Command & Conquer: Tibetan Dawn and Command & Conquer: Red Alert publicly available. This code should help the game community to develop mods and maps, create custom units, and customize the gameplay logic. We all now have a unique opportunity to plunge into the history of development, which is very different from the modern one. Back then, there was no StackOverflow site, convenient code editors, or powerful compilers. Moreover, at that time, there were no static analyzers, and the first thing the community will face is hundreds of errors in the code. This is what the PVS-Studio team will help you with by pointing out the erroneous places.
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Total votes 2: ↑2 and ↓0+2
Comments1

How to find errors in a C# project working under Linux and macOS

Reading time19 min
Views804
PVS-Studio corporate blog.NET*C#*Development for Linux*Development for MacOS*

Picture 8

PVS-Studio is a well-known static code analyzer that allows you to find a lot of tricky errors hidden in the source code. Beta testing of the new version has recently finished. It provides the possibility to analyze C# projects under Linux and macOS. The tool can also be integrated into the cross-platform IDE from JetBrains — Rider. This article will help you to get acquainted with these features using the example of checking the open source RavenDB project.
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Locks in PostgreSQL: 4. Locks in memory

Reading time10 min
Views16K
Postgres Professional corporate blogPostgreSQL*SQL*
Translation
To remind you, we've already talked about relation-level locks, row-level locks, locks on other objects (including predicate locks) and interrelationships of different types of locks.

The following discussion of locks in RAM finishes this series of articles. We will consider spinlocks, lightweight locks and buffer pins, as well as events monitoring tools and sampling.


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