How do Plagiarism Checker Work

by on October 26, 2021

Today, almost all educational institutions require original texts of term and diploma theses, essays, reports, and labs. In checking the originality of all rely on the system to check the uniqueness of the text (or anti-plagiarism), but few people understand how anti-plagiarism.

So what does the anti-plagiarism system? Let’s find out.

Plagiarism systems only check the uniqueness of the text

It’s funny, but the notorious plagiarism has nothing to do with checking the text for the presence of plagiarism. Judge for yourself: plagiarism – a theft, that is, when you took someone else’s something and pass it off as your own. If you give any anti-plagiarism system two texts (the original and the rewrite), none of them will say where the original is. Due to technical features, they can only determine the proportion of borrowed text – any text that is on the Internet or in their databases.

What about uniqueness?

This share of borrowed text is unique. The fewer text borrows, the higher it is.

There are two types of uniqueness:

  • Technical uniqueness. When they say the uniqueness of the text in most cases they mean it. This kind of uniqueness is evaluated on technical indicators such as text structure, the set and order of words, and so on. The meaning of the text may not be unique and in this or that way lit in other materials.
  • Meaningful uniqueness. If the text has information that has not previously existed anywhere, then it has a high semantic uniqueness. Anti-plagiarism systems ignore it because to evaluate the semantic uniqueness of the text you must understand the content. Such uniqueness plays a role on the Internet, in the texts read by thousands of people. And when they check academic papers on her just hammer.

How systems check the uniqueness of the text

Plagiarism systems use complex algorithms to check for uniqueness. Usually, I use it when someone help me write my paper. The most common is the algorithm (or method) of shingles. The essence of this method comes down to finding literal matches. The program divides the text into small pieces (shingles), consisting of a certain number of words. These shingles have words in common with one another – they are like scales superimposed on one another so that not a single word remains untested.

How anti-plagiarism works. Shingles

A special unique set of letters and numbers is calculated for each shingle, encrypting the contents of this piece of text. One text cannot contain two shingles with a unique hash.

How anti-plagiarism works. Shingle hashes.

And here’s how the check works: the service takes your text and the text it considers similar and starts comparing the hashes of the individual shingles. The more matches, the lower the uniqueness and the higher the probability that one of the texts is a copy of the other (maybe not completely, but partially).

You can find even slightly modified texts with the help of the shingle algorithm – that is why it is so popular. But it is not without disadvantages: the shingle method fails when it is necessary to select quotations, phrases, and other stable expressions from the text. Therefore, if you try to check the text of a textbook, say, on medicine, the anti-plagiarism system is likely to show low uniqueness – all because of the use of stable expressions in the text, typical for the subject. And it seems that everyone understands that without such expressions cannot go anywhere, but uniqueness is kind to tighten.

In addition to the standard method of shingles, services reinvent themselves and add additional ways to check. For example, the algorithm of lexical matching searches for similar terms and concepts in the text. And a pseudo-uniqueness algorithm helps identify text that has been processed by a uniqueness increase service.

Some uniqueness checking services have more advanced methods. For example, some systems of anti-plagiarism cannot be created simply by changing the order of sentences, phrases, or words, changing cases, tenses, or adding new words to the text.

The easiest way to get a good result when checking the text for uniqueness – write it yourself and as little as possible to rely on other materials. However, when you write an essay, term paper, or diploma, it’s difficult not to rely on books, manuals, and so on.

Our advice: just don’t tear out whole chunks of text to insert into your academic work. It is better to delve into the text, let it flow through you, and write it down in your own words.