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"Plagiarism Detector" - Bugs\Errors\Crashes / Problem with V895
« Last post by Stella.Kritsotaki on November 14, 2015, 02:59:55 PM »
I wrote to your support team

"I bought  “Plagiarism-detector” on January 4th of 2014 as you can see on the attached mails I received. Until now I was very happy with the product. I have a small business that prepares academic essays and helps students prepare their own original essays. From the 5th  November when I downloaded your last file “pd_setup” I am facing problems. The reason is that the programs distinguishes between arts and sciences and has two options of comparing essays. The science version detects only “word to word” exactness while the arts version is very sensitive in paraphrasing the same answer and shows very high plagiarism percentages. These high percentages of the Arts version are not reliable because the answers of the students are the same – because the questions are the same - but written with completely different words and in completely different style. So these 2 seperate versions are not suitable for me because the science is much less sensitive and the arts much more sensitive than  appropriate to let’s say check a marketing essay that students are obliged to answer the same questions so they have to say the same things more or less. The problem would be solved if I was able to work with the previous version however the program leaves me no option to avoid downloading the new one.
I see these solutions: Solution1 to be able to work with the previous version and avoid downloading the new version
Solution 2: Decrease the sensitivity of the arts version so as to reflect the sensitivity of the old version.
I am waiting to hearing from you soon because these last days I am doing only manual plagiarism and it is very tiring and time consuming."

The answer is:
Thank you for the detailed feedback.
We will consider decreasing detection rates for the Arts, as this is not the first request like this.

As for providing the previous version - unfortunately that is not an option. Due to some third party changes, older version now have a very poor detection rate. That is why we have enabled force update to the current version.

My new question: Since until then the program is useless to me when can i expect such a decreased detection or at least the ability to manually adjust it. You understand that if nothing happends within let's say a week i will switch to another program and would definatelly not recommend yours. Mistakes should be corrected!
"Plagiarism Detector" general discussion / Re: license Difference
« Last post by Alexei B. on November 04, 2015, 01:03:36 PM »
Thank you for your interest in our software!

Lite is the most basic license. We are now reviewing differences between Lite and Personal licenses, so these will be different in the next version.

Pro - this license gives access to all features, and besides provides licenses for two computers.

Portable - this gives additional license to be used from your USB/Flash drive.

All the prices are available from our site:

Feel free to ask any additional questions.
"Plagiarism Detector" general discussion / license Difference
« Last post by boyosof on October 29, 2015, 09:44:01 AM »
I want to know what is the difference between :
lite license and personal license ?
Versions - Release History / PDC core versions 888-889 - major update
« Last post by Alexei B. on September 24, 2015, 03:43:16 PM »
Plagiarism Detector major update with core version 888:


01. Added check type selection window to the Step-by-Step Wizard. More details here:,337.
02. Added failed resources notification. More details here:,48.0.html
03. New T-comparator is now used for comparing documents. It is more precise, yet creates more load on CPU and memory. Due to this change, results from previous versions can differ from current results.
04. Changed license information text on the mains screen to avoid misunderstanding

1. Fixed an issue, resulting from third-party changes, that made previous versions returning "no plagiarism" results for most document. Force-updating from previous versions due to this fix.

We are highly looking towards your feedback!
"Silver Bullets" / Re: Check Type: Word-to-Word VS Re-Written
« Last post by Alexei B. on September 18, 2015, 05:03:31 PM »
The Exact Sciences.

Text in these fields of knowledge showed certain features of their own, making the above-mentioned obfuscated Plagiarism detection algorithms unacceptable on many cases. Texts in Physics, Maths, etc. usually are much less flexible and enjoy a massive use of domain-specific constructions and expressions that are similar to many texts from the same domain of knowledge. One of the best examples was a certain medical prescription, which was considered Plagiarized upon checking. However a manual check did not confirm it. It turned out that most (if not all) of prescriptions use the same structure of the text as well as the same words and expressions. It is just the components, that change.

Let us take this example from Wikipedia:
“Take of pentobarbitone sodium, three grammes
of sulphate of morphia, two grammes
of hydrate of chloral, fifteen grammes
of table sugar, enough to make fifty grammes.”
And now let’s toss the ingredients randomly:
“Take of hydrate of chloral, three grammes
of pentobarbitone sodium, two grammes
of sulphate of morphia, fifty grammes
of table sugar, enough to make fifteen grammes.”

And now remember the example from the Arts section that was to be detected as Plagiarism. It is rather evident, that due to the same language used these parts will be considered the “same” text, that was obfuscated by changing the word order (one of the approached to obfuscation).

Sure, it is an error, one that we call false-positive. Errors of this kind are usual for all the Plagiarism detection algorithms that are aimed at detecting obfuscated Plagiarism.

Having it in mind, we modified the algorithm specifically for such texts, to detect only what we call “word-to-word” Plagiarism. This algorithm will correctly detect this “prescription” as two different texts, but will also detect those “Arts” example as different texts.

So this “word-to-word” Plagiarism Detection algorithm has the following features:
-   Detects only similar parts of texts
-   Prevents false-positive results
-   Usually shows less Plagiarism then a regular algorithm
-   Is bad at finding even slightly obfuscated Plagiarism

In the recent years we have had several versions of Plagiarism Detector, using this algorithm, and they were provided to customers, that required this kind of check. However having two very different versions is not what we see right, so our RnD spent much time on incorporating both algorithms into a single software!

"Silver Bullets" / Re: Check Type: Word-to-Word VS Re-Written
« Last post by Alexei B. on September 18, 2015, 05:02:28 PM »
The Arts.

Texts in these subjects are very flexible in nature and allow much modification without actually changing the meaning. Any analysis of a piece of literature is a good example to it. To detect Plagiarism in a best possible way a software has to detect obfuscated “re-written” cases of Plagiarism – when sentences are modified (manually or automatically) to keep the meaning, but avoid detection. We have multiple cases of such modified documents, provided by our customers at different times, which shows some students’ struggle to avoid Plagiarism detection. For example the sentence “It was a need for him to have the computer fixed” is better be detected as similar to “he must have had the PC fixed”. Please note: these examples are hypothetical and very simplified, the algorithm is much more complex and this pair can be detected or not, depending on the context.

Such approach to Plagiarism detection is perceived to be better not only by us, but also by many competitors, and that is due to several advantages:
-   Obfuscated Plagiarism detection
-   More Plagiarism detected – users often compare software by the detection percent for the same document

That is why it has usually been a default setting for our software.
However, this approach was found to have a significant drawback:
-   False-positive results for certain documents (see below)
"Silver Bullets" / Check Type: Word-to-Word VS Re-Written
« Last post by Alexei B. on September 18, 2015, 12:32:09 AM »
Plagiarism Detector team is proud to announce the absolutely awesome feature added to Plagiarism Detector – presets for different kinds of documents are now available “out of the box”!

Some theory behind this:
It has been some time, since we first observed cases, when our usual Plagiarism detection algorithms provided unsatisfactory results for certain documents. Additional research highlighted some common features for such cases. These are the specific features of the text in the Arts subjects and Exact Sciences subjects, as we started to call them. While the language for these documents is the same, they usually have some very interesting characteristics, which require different attitude from the Plagiarism detection algorithms.

So, starting with version 885, a user can select the preferable algorithm of check in the Step-by-Step Wizard! Please select “detect Text Rewrite (maximum detection)” if you documents are in the Arts subjects or other similar, and “detect Word-to-Word (maximum exactness)” if your documents are in the Exact Sciences’ fields.

We really believe that this new feature (that we have never seen before elsewhere) will help our customers in the ever-ongoing struggle against copy-paste!

"Plagiarism Detector" installation issues / Notron Antivirus and PD setup package
« Last post by Alexei B. on September 02, 2015, 02:41:27 PM »
We are aware of the false-positive Norton alert about the setup-file (at the time of posting, v885).

You are most likely to see the WS.Reputation.1 as the alert reason. It looks like Norton react to our file, as we have released a new version and their anti-virus software is not "familiar" with it.

You can read more on the problem here:

There should be an option to remove the file from Quarantine, which would allow you to use it.

We are sure the install package for our software does not have any virus inside, as the online-service confirms:

We see it possible later setups can also be falsely detected, so client are encouraged to use VirusTotal for checks.

We hope it helps.
Just discussed the situation with RnD.

1. Some kind of detailed setting to the T-Comparator is planned for the future.

2. Please provide a pair of reports (old-new) with a detailed explanation to what is wrong to our support e-mail (check forum PM). Our RnD requests that a problem is described so that we can be sure that "this" is what you are writing about. Screenshots may help much.

Any user-provided materials are used for internal testing only.
"Plagiarism Detector" - Bugs\Errors\Crashes / Re: T-Comparator config in version 885
« Last post by dncom on August 25, 2015, 07:44:19 AM »
Thank you but it still does not address my problem. I bought two copies of the software and both are now useless to use in checking student assignments. The reason fore this is that I cannot understand the results as it shows high plagiarism where there is little or none. I tested it by passing through old assignments that had been tested on the older version. It now indicates a higher level of plagiarism than before but when I look at the comparison report, it does not indicate that high level.

Either bring back the old method of being able to adjust the T-camparator parameters or post a detailed explanation of how things work now and on how to adjust any settings. PD is now useless to me and I am investigating other software. I have also stopped recommending it to other lecturers.

Please do something to restore PD's integrity...
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