Wikidata Visualization for Event and Temporal Data Exploration in Digital Humanities and Cultural Heritage

The paper presents an original and relevant contribution, well-positioned within the domain of Digital Humanities (DH) and Cultural Heritage (CH), with a specific focus on Wikidata and the temporal representation/visualisation of events. The work stands out for its user-centred approach and comparative analysis of existing tools, culminating in developing and evaluating the ReKisstory tool.

The article is well structured, with a coherent narrative flow. The ReKisstory tool demonstrates technical maturity, and the seven time-related features (F1–F7) are relevant and well illustrated.

However, I suggest improving the following aspects:

Clarify whether the cited tools (e.g., yaap!, Histomania) are free to use or offer a free plan.

The user analysis is well conducted, but it would be helpful to clarify how the 14 requirements (R1–R14) were selected from a methodological perspective.

The authors state: "For the same performance reasons, we deliberately disabled the inference function for the SPARQL queries in the Find section (40). This is a well-known technical problem for LD implementers." --> I recommend explaining this technical issue in more detail.

The article shows promising alignment with Open Science principles, but there are areas where this could be made more explicit:

- Is ReKisstory accessible online? If so, please add a link to the GitHub repository or a dedicated webpage.

- It would also be beneficial to clearly state whether the code for ReKisstory is open source and under which license.

- If the tool is not publicly accessible or open source, the authors should briefly explain why.

Minor suggestions:

- Figure 3: Improve the legibility of the central dotted frame.

- Add the missing bibliographic reference for Whitelaw (R2).

- Replace the API link reported in reference (44) with the more user-friendly one: https://wikidata.reconci.link/

- The sentence: "the event entity of Siege of Vienna … that appear as a subject" should be corrected to "the event entity of the Siege of Vienna … appears as a subject.".

- Ensure consistency in the use of quotation marks.

- Correct the typo in: "using/requiring advanced advanced SPARQL." → “using/requiring advanced SPARQL.".

- Finally, I would like to suggest that the authors consider this tool, which may be of interest, as it integrates Wikidata entities into semantic narratives of Cultural Heritage (CH) objects and visualises them as story maps and timelines: https://dlnarratives.eu/tool.html.

This paper presents a visualization tool for Wikidata, tailored for research in Cultural Heritage (CH) and Digital Humanities (DH). It is submitted to the special issue on the Semantic Web and Ontology Design for Cultural Heritage. It is quite relevant to the topic area “Semantic Web Technologies and Applications for Cultural Heritage”, and more particularly to the topics “Searching, querying and visualising CH data on the SW”, “Navigating through and browsing CH data on the Web”, and “SW applications for digital libraries, museums, tourism, the creative industries, etc.”.
The paper focuses on the visualization of temporal data from Wikidata. Section 2 presents a literature review of existing DH and CH projects using Wikidata and visualization tools for Wikidata to assess their capabilities in handling event data. Section 3 first presents 14 requirements identified in the literature or derived from the authors’ analysis of existing tools, and then the design of the proposed visualization tool for Wikidata and 7 time-related features required for DH and CH research. Section 4 presents a user evaluation of these features relying on focus groups involving DH and CH experts and questionnaires. Section 5 discusses the results and section 6 concludes.
The paper is very well written, interesting, agreeable to read, its organisation is outstanding.
The analysis of Wikidata-centric DH and CH projects and visualization tools handling event data, the identification of requirements and associated features and the developed tool represent an original and significant contribution.
The authors show very clearly how the design and features of the proposed tool responds to the identified requirements and the results of the evaluation are very well discussed.
Minor comments:
A table summarizing the comparison of the proposed visualization tool to state of the art tools on the identified features and /or requirements would be valuable.
Wikidata is chosen as a case study. The paper should discuss to which extend the tool can be used to visualize event data from other KG.
The proposed tool is primarily dedicated to CH and DH research. The paper should discuss in conclusion to which extent it is finally specific to these domains or can be used in other research domains considering event data, e.g. archaeology, life sciences, history of science, etc.
Typos:
Missing comma between first and second author
P3 that appear -> appears,
P3 wrong opening quote for 1485… and extra closing bracket
P3 is a person type -> is of type person
P3 again wrong opening quote for 1947… and useless brackets
P3 between person time and place -> a person, a time and a place
Listing 3: it would be vmore clear to provide all the corresponding code for statement C
Figure 1: the 2 screenshots (Vienna and Bowie) should be better separated and what are references should be explained in the text.
P6 R14: However, … -> rephrase
Figure 2, legend: max -> up to, calculation -> its
Figure 6: separate the 2 screenshots. I do not understand the one on the right
P9 references 12 and 13 should be more specific
P 11 to the question to the question

*SUMMARY*
This paper presents a tool designed to support the exploration and visualization of event and time-related data in Wikidata, particularly within the contexts of Digital Humanities (DH) and Cultural Heritage (CH). The authors define 14 functional requirements and implement 7 time-related features to support user interaction and semantic analysis. They conduct a user evaluation via surveys and workshops with domain experts, aiming to identify usability and value of the tool in real-world research tasks.

*ORIGINALITY*
The paper combines ideas from information visualization and Linked Data tools to create a user-friendly interface for exploring events and time-related data in Wikidata. It focuses on helping non-technical users in DH/CH, filling a known gap in this domain. However, while the tool offers new combinations of features, many of the implemented ideas are known in the field. Thus, the originality lies more in the integration, interface design, and evaluation for a particular audience than in foundational technical innovation

*SIGNIFICANCE OF THE RESULTS*
The presented work demonstrates good potential for reuse and extension in other Linked Data visualization contexts. Its alignment with practices in DH and CH makes it a valuable contribution to the cross-disciplinary adoption of semantic technologies. The authors are transparent about the tool’s current immaturity, which limits its immediate impact. Issues such as performance bottlenecks, interface bugs (e.g., auto-suggest), and SPARQL timeouts noticeably affect the user experience and would need to be improved. The evaluation offers insightful, though preliminary, feedback. The methodology (based on pre and post workshops) is sound. However, the evaluation would benefit from a larger sample size (especially post-workshop, with only 11 responses) and from the inclusion of more quantitative metrics or task-based performance benchmarks.

*QUALITY OF WRITING*
The paper is generally well-written. Below, I report some issues affecting its polish:
- Inconsistent punctuation across figure captions and footnotes, and misformatted quotation marks (e.g., on pages 11 and 13)
- Questionnaire labels Q1 and Q2 are only introduced in Table 1. These should be defined clearly in the main text and consistently referred to throughout.
- pag. 9 has an unmatched parenthesis: “(the first and second questionnaire (49)” should be corrected.
- Reference (49) to the Zenodo repository is cited repeatedly, sometimes unnecessarily.
- Figures' captions can be improved by adding key information, such as what colours represent in demographic charts. For example, in Figure 10, clarify which group is shown in orange and which in blue (Q1 vs Q2).
- The current description of the evaluation is somewhat scattered. The authors should consider to restructure it using a clearer flow: objectives, participants, method, etc.

*DATA ARTIFACTS*
The Zenodo repository includes relevant resources (e.g., questionnaires, workshop materials, and user feedback). However, its description could be enhanced to more clearly outline the structure of these resources.

This paper addresses a relevant aspect of Linked Data visualization in the context of DH and CH. With some revisions to improve the clarity of the work, it would be suitable for publication.