PPROC, an Ontology for Transparency in Public Procurement

Tracking #: 895-2106

Jose Felix Munoz Soro
Guillermo Esteban
Oscar Corcho
Francisco Serón

Responsible editor: 
Guest editors Semantic Web 4 Legal Domain

Submission type: 
Full Paper
Public procurement or tendering refers to the process followed by public authorities for the procurement of goods and services. Most public authorities in developed countries provide online services to facilitate this process (e.g., available at the buyer profiles of public authorities), as well as to ensure as much as possible competitive tendering (for which an adequate advertisement of tenders is an essential requirement). Besides, transparency laws being proposed in such countries are making the monitoring of public contracts by citizens an essential right as well. This paper describes the PPROC ontology, which has been developed to give support to both processes (advertising and accounting), by semantically describing public procurement processes and contracts. The PPROC ontology is extensive, since it covers not only the usual data about the tender, its objectives, deadlines, and awardees, but also details of the whole process followed from the contract initial publication to its termination. This makes it possible to use the ontology both for open data publication purposes (as others in the state of the art) and for the whole management of the public contract procurement process.
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Major Revision

Solicited Reviews:
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Review #1
Anonymous submitted on 21/Dec/2014
Review Comment:

The paper describes the ontology engineering creation process of the PPROC ontology for transparency in public procurement. The concepts and properties used in the ontology are described in motivated and the alignment to other ontologies is addressed. Moreover, the actual application of the ontology in the generation of machine-readable data from two Spanish public authorities is shown, and some meaningful queries on such kind of data are proposed. A discussion ends the paper.

The paper is well written, motivated, and structured. First, the related work, i.e., two ontologies developed with similar purposes, are described and compared to each other. Second, the PPROC ontology is detailed and each class/property introduced in the ontology is motivated. Third, a JSON-LD data sample of a contract from the Zaragoza city council is presented, followed by the list of relevant information that can be extracted through SPARQL queries from such a kind of machine-readable data.

The paper shows how Semantic Web, and in particularly ontology engineering, can help in improving the treatment of legal information, and for this reason I believe that the paper well suits the purpose of this special issue and should be accepted. What I appreciate is that, differently from many other papers introducing new ontologies, in this case the ontology is well motivated and not only described, and it has been actually used in real world scenarios, resulting in two SPARQL endpoints and the data they allow to query.

Few minor drawbacks can be highlighted and have to be addressed before publishing the final version of the paper:
(1) the list of requirements identified by the stakeholders consulted during the first phase of the ontology conception should be explicitly listed and discussed in the paper. This is the first real step in the definition of the ontology, and more details are needed. Some scenarios highlighted by the stakeholders should also be added at the beginning of the paper to improve the reader's understanding about the context where the ontology will be used.
(2) The textual version of the contract then translated into the machine-readable JASON-LD one of sec. 5.1 should be added at the beginning of the section, to allow the reader to understand the starting text and the complexity of "translating" it into the JASON-LD version exploiting the PPROC ontology. Moreover, some kind of description of the resulting machine-readable contract would improve this section. On this point, it would be interesting also to have some more words about the "translation" process: is it done manually (I think so)? Who is in charge of this step? Is it difficult for them to move from the natural language description of the contract to the machine-readable one?
(3) Some of the SPARQL queries should be added in sec. 5.2.

Minor issues:
1) Figures 1-2 are small and the text is difficult to read.
2) List of lasts contracts -> list of last contracts
3) Count of contract by procedure -> contracts by procedure

Review #2
By Axel Polleres submitted on 22/Dec/2014
Major Revision
Review Comment:

This manuscript was submitted as 'full paper' and should be reviewed along the usual dimensions for research contributions which include (1) originality, (2) significance of the results, and (3) quality of writing.

I think (1) and (3) are ticked ... but I have some doubts still on (2).

I think this project ticks most boxes of a dataset description paper, but still I think it needs more effort to qualify for a journal publication. As it stands, I am not sure it covers the well-established and -used datasets we are looking for in the "dataset descriptions" call of SWJ.

The paper presents a solidly engineered data model/ontology for modeling data about public procurement. Related works seems to be covered sufficiently. What I am missing is proof of usage, beyond the ontology alone being published and the data with the scope of a particular region participating in a research project.

While the authors report some such usage in section 5, it is still somewhat limited to the use case of the project it was developed in. So, what I'd like to see in a revision would be transferrable re-use of the ontology somewhere else.

I would have some concrete suggestion how to change/overcome this limitation.
For instance, the authros could contact similar efforts internationally and agree to model datasets about public procurement across countries and regions in this ontology as linked data.
That is, other open data linked to this ontology, making data comparable across regions could really provide the value of the ontology and dataset I am currently still missing.

E.g. in Austria, there is a similar project called https://www.offenerhaushalt.at/ who could be interested in collaboration.

Review #3
By Angelo Di Iorio submitted on 09/Jan/2015
Major Revision
Review Comment:

The paper introduces an ontology for the description of public procurement, currently used by two Spanish institutions. It describes the process and the ontology, as well as the two scenarios where the ontology was deployed.

The idea is not particularly innovative and the evaluation is limited but the paper is clear and solid, and I would accept it after a revision. The main issue is that the ontology has not fully proved to be effective and applicable to other contexts.
The evaluation part has to be extended. The authors should discuss the size of the produced datasets, the amount (and quality) of information published in PPROC, to what extent the datasets have been exploited for services to the citizens, which data have been used, how they have been accessed, and so on.
Another aspect that should be investigated is the applicability and extensibility of PPROC to contracts of other EU countries or non-EU ones.

I like the idea of ‘institution-oriented’ ontology. Instead of bringing it in the conclusions, I would suggest authors to move it at the beginning and to highlight it. That is a key (innovative) aspect of the ontology and would strengthen the overall work. Yes, there is a mention at the end of the introduction and of section 2 but it is not very clear.

The comparison to the state-of-the-art is another aspect that could be improved. The authors mention MOLDEAS and ‘several other projects’ on the procurement process, but they do not explain why these projects (and the models behind them) were not investigated. It is not clear why the analysis is limited to PCO and LOTED2. A larger related works section is needed, especially in a journal paper. The authors should also say more about the ontologies they used in PPROC.

There is also another issue to investigate. The PPROC ontology by itself does not impose authorities to publish some information about procurement. That is regulated by law (and might change from one country to another one, and from one authority to another) and consequently expressed into the ontology. The authors should distinguish between what is mandatory/optional by law and how that information was translated in PPROC. Some more examples could be useful in that respect.
Section 4.1 also needs some rework. In particular, Figure 1 suggests a hierarchical organization between all core classes. Even if the property subClassOf only holds between pc:Contract and pproc:Contract the picture is misleading. Some more explanation should also be added in the text flow and, in particular, the authors should clarify the relation with the following subsections and explanations.
Section 4.2 should clearly explain where the proposed contracts’ classification derives from. In general, I would suggest authors to add one example (or more) in Section 4 and to incrementally explain how it was built and encoded in PPROC. The long example in Section 5.1 is more difficult to follow, compared to a step-by-step analysis.
Section 4.5 should definitely be extended. The abstract mentions ‘details of the whole process’ but the discussion is very short. Especially it this is a novel contribution of this work, it should be given more space and relevance.

- abstract: the sentences between round brackets could be removed in order to make it clearer and more incisive
- introduction: some EU directives are mentioned but references are missing. In the same sentence, the authors mention ‘certain information that have to be published’. Some more explanations and examples would be helpful.
- Introduction: the part “One of the currently… … … … , it is enough to publish a limited set of announcements” is not clear. Please rephrase.
- In section 3, does it make sense to add a picture depicting the whole development process? Also, it seems that at least two revisions of the ontology were produced. Is that correct?
- Section 4.3 starts with “Two different approaches” and later describes the first one. It is not very clear which is the second one.
- Section 5: The paragraph “Besides these competency… … … to applicable freedon-of-information laws” is not clear. Please rephrase.
- Conclusion: a reference to ‘operational families’ is missing


A set of transparency-oriented views have been made available, supported by the use of the PPROC ontology, at:
(sorry, in Spanish only)