T 1125/17 (Parallelizing computation graphs/AB INITIO) 02-04-2019

The invention

1. The application generally relates to computation graphs in which the vertices and the links define, respectively, "data processing elements" and the data flow between them (see paragraphs 3, 4 and 7).

1.1 In this context, the application relates to the transformation of "serial computation graphs" into "parallel computation graphs".

1.2 Figure 1A depicts a simple "serial" computation graph in which two components A and B are connected by a single "serial link" (see paragraph 4). It is observed that data may sometimes be processed in parallel by different "instances of individual components" A and B, the possible "degree of parallelism" depending on the "characteristics" of A, B and the connection between them (see paragraphs 5 and 30 but also figure 3, no. 330). Making this parallelism explicit in the computation graph yields a "parallel[ized] computation graph" (see figure 1B, 2A, 2B; paragraphs 4-6, 29, 36 and 37), which can also be represented in "serial form" (see paragraphs 39 and 54).

1.3 The data flow in parallel computation graphs is represented using data flow elements referred to as "partition", "gather" and "interconnection" (see figures 1B and 1C, nos. 115 and 135; figures 2B and 2C, no. 225). Several types of each of these elements are anticipated, depending on the type of computation (see paragraphs 30-32, 35, 49).

1.4 The invention means to propose a procedure for the transformation of serial computation graphs into equivalent parallel ones (see figure 3). The procedure may be able to rely on user annotations, indications or other metadata (see paragraphs 43-49 and 51-52) but may also have to make do without them (paragraphs 64-66).

1.5 The procedure according to figure 3 cycles through the "links" in the given serial graph and determines the required partition, interconnection and gather elements (see paragraph 53).

Clarity, Article 84 EPC 1973, and claim construction

2. The claimed method works by iteration over "linking elements" and "determining" various "data processing characteristics" which were "undetermined" before, in particular, "a degree of parallelism", "input requirements" and "sort requirements".

2.1 Claim 1 of the main request and auxiliary requests 1-4 leaves open how these characteristics are determined. Claim 1 of auxiliary request 5 specifies that the determining is based on "metadata" which, according to the description, may be provided manually by the user, i.e. the programmer (loc. cit.). Although the appellant insisted during oral proceedings that the determination could also rely on sources of information other than user annotations, no further explanations were given on how that was meant to be done. Neither does the description which supports the appellant's argument disclose details in this regard (see paragraphs 64 to 66). Either way, no amended claim 1 was filed containing a pertinent amendment. Therefore, claim 1 of all requests is at least consistent with the assumption that the "determining" step essentially retrieves user-provided metadata from the user-specified graph.

2.2 Claim 1 of the main request and auxiliary requests 1-4 does not define the characteristics to be determined. For instance, the "degree of parallelism" is only defined in claim 1 of auxiliary request 5 which states it to specify the desired number - m and n, respectively - of upstream and downstream processing elements.

2.3 Moreover, claim 1 of the main request and auxiliary requests 1-3 fails to specify what happens with the determined characteristics. The step of "inserting the parallelized inter-component link" is merely said to be "configur[ed] according to the data processing characteristics", but how this is done is not stated.

2.4 This constitutes a lack of essential features and renders claim 1 of the main request and auxiliary requests 1-3 unclear, Article 84 EPC 1973. Moreover, because neither the data processing characteristics nor their use in configuring the parallelized inter-component link are defined, the skilled person would not have been able to carry out the invention in its full breadth, in violation of Article 83 EPC 1973.

Article 123(2) EPC

3. Claim 1 of auxiliary request 3 contains the phrase "configuring the parallelized inter-component link for parallel execution on at least two separate processors". As its basis, the appellant refers to paragraph 20 of the application as filed.

3.1 Apart from the fact that a graph "configur[ed] for parallel execution" is not necessarily executed in parallel, paragraph 20 does not specifically disclose the "parallelized inter-component link" to be distributed but, more generally, the "computations specified by an initial serial [or parallel] computation graph".

3.2 The amendments made to claim 1 of auxiliary request 1 thus do not comply with Article 123(2) EPC.

4. Claim 1 of auxiliary request 4 was amended by incorporation of "features relating specifically to the execution of the resulting parallel computation graph[,] based upon material found in reference document US 5966072" (see page 7 of the letter of 4 March 2019, section entitled "Amendments", paragraph 3). This document is assigned to the present appellant and is mentioned in paragraph 3 of the present application documents as originally filed by the brief statement that "A system that implements such graph-based computation is described in U.S. Patent 5,966,072 EXECUTING COMPUTATIONS EXPRESSED AS GRAPHS".

4.1 It is established jurisprudence of the boards of appeal that an amendment in conformance with Article 123(2) may only be made within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from the whole of these documents as filed" (G 2/10, point 4.3 of the reasons).

4.2 When protection is sought for features which were not expressly disclosed in the application documents as originally filed but were taken from a cross-referenced document, it has further been established to use the criteria defined in T 689/90 (catchword 2). This decision is also mentioned in the appellant's letter of 4 March 2019 (bottom of page 7). During the oral proceedings, the appellant made further reference to T 1415/07 and T 288/84 to support its case.

4.3 In accordance with T 689/90, an amendment based on a feature only described in a cross-referenced document is only allowable "if the description of the invention as filed leaves no doubt to a skilled reader", inter alia, "(a) that protection is or may be sought for such features" and "(c) that such features implicitly clearly belong to the description of the invention contained in the application as filed [...] and thus to the content of the application as filed".

4.4 The application states specifically that the contents of the U.S. Provisional Application of which it claims the benefit is "incorporated [...] by reference" (para­graph 1). This statement means to make the content of the provisional application part of the content of the present one. While it is open to argument which features specifically, if any, are (or can) be made part of the content of an application by way of a generic reference like this, this statement is notably missing from paragraph 3. That is, US 5 966 072 is not stated to be incorporated by reference.

4.5 In compliance with the strict standard regarding added matter (see point 3.1 above), requirement (a) is very stringent. It requires that the description "leaves no doubt to a skilled reader" that protection is or may be sought for the pertinent features. In the words of T 1415/07 (point 19 of the reasons), "it must be unambiguously derivable to the skilled person which features of the application are to be taken from the referenced document". A mere mention of a prior art document as an "example" is normally insufficient to identify which features or groups of features are of particular relevance for the citing application, espe­cially if, as in the case at hand, the cited documents contains 32 pages. Also, absent any express indication in the citing application, the disclosure of the abstract and the summary from which the pertinent features were taken cannot be understood to form part of the content of the citing application (requirement (c)).

4.6 Thus, the brief mention of the U.S. patent 5 966 072 in the application at hand is insufficient to make any specific features disclosed in the mentioned patent part of the content of the application as originally filed.

4.7 The situation underlying T 288/84 does not, in the board's judgment, withstand this finding. In that case, the insertion of a single word into the claims was allowed under Article 123(2) EPC because the underlying concept was disclosed in all examples of the application, albeit without expressly mentioning it by name (see point 6.4 of the reasons). In other words, the board in case T 288/84 essentially decided that it was allowable to insert the name of a particular concept that was, without being named, clearly disclosed.

4.8 In the present case, paragraph 20 discloses that "the computation specified by a serial computation graph can be distributed for parallel execution on a number of separate processors". This statement as such is very broad and does not imply which components of the graph are or might be deployed on separate processors. Furthermore, the general reference in paragraph 3 of the present application to "a system that implements [...] graph-based computation" does not imply, without doubt, that the relevant features in the U.S. patent relate to how a parallel computation graph is distributed for parallel computation.

4.9 As a consequence, in view of the fact that the amendments made to claim 1 of auxiliary request 4 crucially rely on that U.S. patent and with no other basis for the added claim language being given, claim 1 of auxiliary request 4 does not comply with Article 123(2) EPC.

Inventive step, Article 56 EPC 1973

5. The amendments made to claim 1 of auxiliary request 5 specify that it is metadata provided in or with the user-specified computation graph which indicates how many upstream or downstream data processing elements there are (i.e., in the terms of figure 1C, how many As and Bs), whether the input flow to any data processing element must be partitioned or sorted and whether every "instance" of a component must receive a copy of each work element. According to the requirements expressed in the metadata, the sorted-merge element is generated. For instance, if the downstream components expect the input to be partitioned differently to how the output of the upstream component is provided, a "hash partition" element is provided which is disclosed to redistribute the work elements according to the required partitions (see paragraph 32).

5.1 This subject-matter specifies (or, rather, is consistent with the assumption) that all information relevant for the automated generation of the parallel computation graph from the user-specified one is already contained explicitly, in the form of user-provided metadata, in the user-specific graph. In other words, the parallel computation graph contains the same amount of information as the user-specified graph and, at best, represents it in an explicit, expanded form. This interpretation was presented to the appellant during oral proceedings and was not challenged.

5.2 The board takes the view that any actual parallel execution of the parallel computation graph is, in principle, also available for the user-specified graph. Hence, whatever speed-up effect can in principle be achieved by parallelizing one graph is not due to the form of the graph but to the details of the user-specified graphs including its metadata.

5.3 Moreover, it is not evident that the expanded form of the graph, the "parallel" computation graph, is, in general, substantially easier to deploy on parallel hardware than the user-specified graph. Such an argument cannot be used for claim 1 as it stands because specifically how the parallel execution graph is deployed on a given hardware is not claimed.

5.4 Thus, the mapping of one graph to another, which is equivalent to expressing the same computation, is, essentially, a mathematical operation on computation graphs, which does not contribute to the effect of parallelization. The transformation itself therefore does not contribute towards inventive step in accordance with the established jurisprudence of the boards of appeal, see T 641/00 (catchword 1).

5.5 Beyond that, the general idea that a computation graph may be executed on some parallel hardware is known in the art (e.g. from the U.S. patent mentioned in paragraph 3 of the application) and therefore obvious as such.

5.6 The subject-matter of claim 1 of auxiliary request 5 thus lacks inventive step, Article 56 EPC 1973.

Further remark

6. During the oral proceedings, in the context of auxiliary request 4, it was discussed whether the transformation of one computation graph into another, without an explicit mention of the deployment of parallel hardware or the execution on parallel hardware, would have to be accepted as a technical effect on the assumption that the generated computation graph was established as lending itself more easily to parallelization than the given one. Although this question turned out not to be decisive for the case at hand, the appellant encouraged the board to comment on this question in its decision.

6.1 The board stresses that, as argued above, it is not convinced of the argument that the generated parallel computation graph is actually easier to parallelize than the given user-specified graph. For this reason alone, the following comment is strictly obiter.

6.2 A computation graph meant to be executed is, essentially, a computer program.

6.3 Even a program written in a programming language with parallelization instructions or with some express potential for parallel execution such as array processing may be executed on parallel hardware or not. Such a program can also be executed on a single-core processor. In this case, a speed-up by parallelization is not achieved. In many cases, a parallel program could be expected to execute more slowly on the single core than an equivalent serial program since any parallelization overhead is not compensated by the speed-up of parallel computation. This is to say that the speed-up of parallelization is not achieved by the form of the parallel program alone and not before the program is actually deployed and executed on parallel hardware.

6.4 In T 1173/97, it was decided that a computer program is not excluded from patentability if, when it is run on a computer, it produces a further technical effect which goes beyond the "normal" physical interactions between program (software) and computer (hardware) (see catchword and point 13 of the reasons).

6.5 This board takes the view that T 1173/97 meant to make this statement only if the mentioned further technical effect was produced whenever the program was run, i.e. on any suitable hardware or runtime environment. For if that effect was produced on a particular execution platform but not on another, the effect could not be attributed to the program itself - unless maybe there was an argument to the effect that the required execution platform was implicit in the program claim. In all other situations, it would seem that the execution platform required to achieve the effect would have to be claimed as an essential feature.

6.6 This would appear to mean that if, as in the present case, an inventive-step argument is to rely upon a speed-up by parallelization, a parallel execution platform must be claimed. Consequently, the mere potential for a speed-up by parallelization would not seem to be sufficient as a "further" technical effect because this effect is not achieved irrespective of how the program is executed.