The European Patent Office refused to grant a software patent for an Internet search engine that improves the quality of the search results. Here are the practical takeaways from the decision T 1849/17 (Search engine with user feedback/PINTEREST) of 12.2.2019 of Technical Board of Appeal 3.5.06:
The application relates to Internet search engines and concerns the problem of improving the perceived quality of the search results. More specifically, the application addresses the problem of making search results more “relevant” for the user. In prior art solutions, discussed in the application, the relevance of a document was assessed on the basis of the content of that document, of links between web pages or the feedback of test users. The invention essentially proposes to allow direct relevance feedback by users on individual results returned in response to a query.
The application proposes modeling the “probability” that a given document is relevant by “logistic regression” based on features of the document such as binary values each indicating the presence or absence of a feature) and “parameters” theta (effectively weights). This model is modified in view of the user feedback, especially the weighted parameter psiu per user u. Users’ feedback may be clustered, for instance in view of groups of users, or in order to detect and exclude search engine optimizers and spammers as outliers due to the “eccentricities in their parameters”. Additional parameters gammac determined per cluster c may be used to adapt the relevance model.
Claim 1 (main request)A method of ranking documents in a results list of documents presented to a user in response to a search query comprising:
a. receiving and storing feedback from the user u regarding a relevance of a document d to the user u, from the search query q, the feedback being represented as a query-document feature (q, d, u) = s, where s is the rating as a number of stars assigned by the user u, and discarding any previous rating for the query-document feature (q, d, u);
b. associating the user feedback s with the search query q and the document d;
c. determining a relevance score for the document d for the query q, for a vector of a plurality of features X of the document d and a vector of the parameters theta for a model for a group of users combined with a specific vector of weighted feedback of a vector of the parameters psi for each user u according to the expression u(X) = 1/[1 + e**(-(theta+psi)*X)]; and
d. ranking the document based on the relevance score.
Is it patentable?
First of all, the Board did not follow the applicant’s argument that the invention results in a faster and more efficient execution of a search:
The appellant argued that the claimed invention provided a “faster and more efficient execution of a search” and a “faster and more efficient ranking” of search results “on a computer”, which had to be considered as technical problems. In particular, the features of “discarding” previous user feedback (see claim 1, step a, last phrase) and that of eliminating “bias” by reference to a “group model” contributed to these effects (see the grounds of appeal, page 2, paragraph 5, and page 5, paragraph 2).
The board does not accept that the search itself executes any “faster” or “more efficient[ly]” due to the claimed relevance feedback, in particular because the search results are ranked after retrieval. Likewise, the ranking itself cannot be said to be determined any “faster” or “more efficient[ly]”, inter alia because the reference for this comparison is not indicated (“faster and more efficient” than what?).
On the one hand, the Board did not rule out that reducing the time until the user finds a hit in the search results may probably be considered technical. However, the Board did ultimately not decide on this question since the effect was found not to be reliably achieved:
Generally speaking, the invention is meant to produce relevant search results quicker (or higher up on the list of results) and thus to reduce the time until a user finds a “hit” in the search results. A relevance feedback that would reliably achieve this effect might save the user certain work, such as clicking through a long list of search results or having to repeat a search. The board does not wish to exclude the possibility that this may be considered as a technical effect by analogy to the ratio of T 0643/00, which is that providing a technical tool for efficient search, retrieval and evaluation of images may be considered a technical problem solved.
This issue need not be decided, however, because it cannot be established that the invention does indeed reliably and reproducibly have the alleged effect. Without knowing any details about how the relevance models are computed from (or based on) the user feedback and how the groups are determined, there is no basis for assessing even the probability that – or in which situations – the relevance feedback would actually be pertinent for an individual user.
The board therefore concludes that the claimed invention cannot be said to have the effect of saving the user work in the above-mentioned sense.
Another feature of the invention was that a previous user rating can be discarded. But also this did not convince the Board:
Likewise, it cannot be established that discarding a previous user rating has this effect. For instance, it is not guaranteed that the last user feedback on a particular document is relevant for the next search. The user might, for instance, in one instance search for holiday destinations and rate highly a document mentioning the country Turkey, and in the next instance look for Thanksgiving recipes and be interested in documents mentioning turkey, the bird.
Thus, the Board took the view that the mathematical model used to determine the relevance of the search results was just a mathematical method as such:
Hence, the board must conclude that the relevance formula (in step c of claim of the main request and auxiliary request 1 or step g of auxiliary 2) is just any mathematical formula – and, as such, excluded from patentability by analogy to the exclusion of Article 52(2)(a) and (3) EPC 1973 – which does not contribute to the technical character of the claimed invention and, therefore, cannot contribute to inventive step (see T 641/00, headnote 1).
Therefore, the Board ultimately decided that the patent application does not provide any technical contribution that could be the basis for an inventive step.
You can read the whole decision here: T 1849/17 (Search engine with user feedback/PINTEREST) of 12.2.2019