Similarity Policy

1. Purpose

Euclid is committed to publishing original and ethically responsible scholarly work. All submitted manuscripts may be screened using recognized similarity-detection software to identify potentially unattributed text, redundant publication, inappropriate text recycling, or other forms of plagiarism.

Similarity screening is intended to support editorial assessment. A similarity score does not, by itself, establish whether plagiarism has occurred. The editorial team will examine the nature, extent, location, source, and context of every significant textual match.

This policy should be read together with the journal’s Publication Ethics and Author Guidelines.

2. Similarity Requirements

As a general requirement, a manuscript submitted to Euclid should meet the following similarity benchmarks:

  • the overall similarity score should not exceed 20%; and

  • similarity originating from any single source should not normally exceed 3%.

These percentages are editorial screening benchmarks rather than automatic measures of plagiarism. A manuscript with a score below the stated threshold may still be rejected if it contains unattributed copying, plagiarism of ideas, translated plagiarism, duplicate publication, or other serious ethical problems.

Conversely, a manuscript with a score above the threshold may be considered further when the matches arise primarily from legitimate and appropriately disclosed materials, such as:

  • references and bibliographic entries;

  • properly cited direct quotations;

  • standard methodological terminology;

  • commonly used mathematical definitions or expressions;

  • names of institutions, instruments, datasets, or regulations;

  • article titles and technical terminology;

  • unavoidable descriptions of standard procedures; or

  • an author’s thesis, dissertation, preprint, or conference paper that has been properly disclosed and cited.

The final determination rests with the editorial team.

3. Materials Considered During Screening

Where technically possible and editorially appropriate, the following elements may be excluded or assessed separately when calculating similarity:

  • the reference list;

  • properly formatted direct quotations;

  • article titles and standard headings;

  • short or incidental matches;

  • mathematical formulas and standard notation;

  • names of research instruments or established methods; and

  • materials explicitly disclosed as an earlier version of the work.

Exclusion by similarity-detection software does not remove the author’s obligation to cite sources accurately and transparently.

4. Interpretation of Similarity Reports

The editorial team will not evaluate similarity solely on the basis of the total percentage. Particular attention will be given to:

  • long passages copied from one or more sources;

  • close paraphrasing without proper attribution;

  • copied structures, arguments, proofs, tables, figures, or datasets;

  • similarity in the results, discussion, or conclusion sections;

  • reuse of previously published work without disclosure;

  • translation of another work without attribution;

  • manipulation intended to evade similarity detection;

  • incorrect, incomplete, or fabricated citations; and

  • the cumulative effect of multiple small matches.

In mathematics manuscripts, similarities involving standard definitions, conventional notation, commonly stated theorems, or standard descriptions of methods will be assessed in their disciplinary context. However, original proofs, derivations, algorithms, models, explanations, examples, and interpretations must not be copied without appropriate acknowledgment.

5. Editorial Actions Based on Similarity

The following actions may be taken after editorial examination:

Overall Similarity of 20% or Less

The manuscript may proceed to editorial assessment or peer review if the matching text is appropriately cited and no evidence of plagiarism or redundant publication is found.

A score within this range does not guarantee that the manuscript will be accepted or sent for peer review.

Overall Similarity Above 20%

The manuscript may be returned to the authors for revision when the matching text appears correctable and does not indicate serious misconduct.

Authors may be asked to:

  • rewrite inadequately paraphrased passages;

  • add missing citations;

  • reduce unnecessary direct quotation;

  • disclose previous versions of the manuscript;

  • clarify the relationship with earlier publications; or

  • provide supporting documentation.

A revised manuscript may be screened again before further editorial consideration.

Substantial or Serious Overlap

A manuscript may be rejected without peer review when the similarity report and editorial assessment indicate substantial unattributed copying, duplicate publication, plagiarism, systematic text recycling, or deliberate manipulation.

Serious cases may be handled according to the journal’s Publication Ethics and relevant guidance from the Committee on Publication Ethics (COPE).

6. Plagiarism

Plagiarism includes, but is not limited to:

  • copying words or sentences without quotation and citation;

  • presenting another person’s ideas, arguments, methods, data, proofs, code, figures, tables, or results as one’s own;

  • closely paraphrasing a source without proper attribution;

  • translating material from another language without citation;

  • copying material from unpublished manuscripts, student work, reports, websites, repositories, or conference papers without acknowledgment;

  • using images, diagrams, instruments, or datasets without permission or attribution where required; and

  • appropriating the structure or central argument of another work without proper acknowledgment.

Providing a citation does not automatically make extensive verbatim copying acceptable. Direct quotations must be clearly marked, used sparingly, and accompanied by an appropriate citation.

7. Self-Plagiarism and Text Recycling

Authors must cite and disclose their own previously published or publicly available work when it is reused in a new manuscript.

Inappropriate text recycling includes:

  • reproducing substantial sections of an earlier publication without citation;

  • republishing the same data or findings as if they were new;

  • submitting substantially similar manuscripts to different journals;

  • dividing one study into several minimally different publications without scholarly justification; and

  • reusing tables, figures, proofs, models, or other materials without disclosure.

Limited reuse of standard methodological descriptions may be acceptable when accurate rewriting would reduce clarity. Such reuse must be kept to the minimum necessary, appropriately cited where applicable, and must not misrepresent previously published work as new.

8. Theses, Dissertations, Preprints, and Conference Papers

A manuscript derived from a thesis, dissertation, preprint, institutional repository, research report, or conference paper may be considered if:

  • the earlier version is disclosed during submission;

  • the source is properly cited when appropriate;

  • the manuscript complies with applicable copyright and licensing requirements;

  • the journal article offers an appropriate and clearly identifiable scholarly contribution; and

  • the manuscript has not already been formally published as a substantially identical journal article.

A textual match with an author’s thesis, dissertation, or legitimate preprint will not automatically be treated as plagiarism. However, the relationship between the submitted manuscript and the earlier version must be transparent.

Authors should explain the source and development of the manuscript in the “Comments for the Editor” field during submission.

9. Conference Proceedings and Previously Published Articles

Manuscripts already published in conference proceedings with an ISBN, ISSN, DOI, or formal publication status will be assessed carefully.

An extended version may be considered only when:

  • the previous publication is fully disclosed and cited;

  • permission has been obtained where required;

  • the submitted manuscript contains substantial new analysis, results, interpretation, or theoretical development; and

  • the manuscript clearly explains how it differs from the earlier publication.

Merely changing the title, abstract, wording, order of authors, or a limited portion of the analysis does not constitute a sufficiently new publication.

10. Manipulation of Similarity Screening

Authors must not attempt to manipulate or evade similarity detection. Prohibited practices include:

  • replacing letters with visually similar characters;

  • inserting invisible characters, spaces, or images of text;

  • deliberately altering spelling to avoid matching;

  • using automated paraphrasing or “text-spinning” tools to disguise copied material;

  • converting copied text into non-editable images;

  • fabricating or replacing citations; and

  • using generative artificial intelligence to conceal plagiarism.

Evidence of deliberate manipulation may result in immediate rejection and further action under the journal’s Publication Ethics.

11. Author Responsibilities

Before submission, authors are responsible for ensuring that:

  • the manuscript represents original scholarly work;

  • all borrowed words, ideas, data, methods, and materials are properly acknowledged;

  • direct quotations are clearly identified;

  • paraphrased material is genuinely rewritten and appropriately cited;

  • previous versions and related publications are disclosed;

  • all co-authors have reviewed and approved the manuscript; and

  • no part of the manuscript infringes copyright or other intellectual-property rights.

Authors are encouraged to conduct their own similarity check before submission. However, a report provided by an author does not replace the journal’s independent screening and editorial assessment.

12. Similarity Detected After Publication

If substantial unattributed overlap or duplicate publication is identified after publication, Euclid will investigate the matter in accordance with its Publication Ethics.

Depending on the nature and seriousness of the issue, the journal may:

  • request an explanation from the authors;

  • publish a correction;

  • publish an expression of concern;

  • retract the article;

  • notify the authors’ institutions, funders, or other relevant parties; or

  • take other appropriate corrective action.

Post-publication action will be based on the available evidence and the effect of the identified problem on the integrity and originality of the published work.

13. Appeals

Authors may appeal a similarity-related editorial decision by submitting a written explanation and relevant evidence to the editorial office.

An appeal should identify:

  • the specific decision being challenged;

  • the sources responsible for the similarity;

  • the reasons the matching material is considered legitimate; and

  • any supporting evidence concerning attribution, prior publication, copyright, or manuscript history.

Appeals will be evaluated by the editorial team. When appropriate, the appeal may be reviewed by an editor who was not directly responsible for the original decision. Submission of an appeal does not guarantee reconsideration or acceptance.

14. Final Editorial Authority

The similarity thresholds stated in this policy are screening benchmarks. They do not replace expert editorial judgment.

The Editor-in-Chief has final authority to determine whether textual overlap is acceptable, requires revision, constitutes plagiarism or redundant publication, or warrants other corrective action. Decisions will consider disciplinary conventions, the manuscript’s publication history, the authors’ explanation, and the principles of fair and responsible scholarly publishing.