The application underlying this decision relates to a sparse neural network architecture. However, the European Patent Office refused to grant a patent since claim 1 specifies an abstract computer-implemented mathematical operation on unspecified data, i.e., approximating the weight values of the network. Here are the practical takeaways of the decision T 0702/20 (Sparsely connected neural network/MITSUBISHI) of November 7, 2022 of Technical Board of Appeal 3.5.06:

Key takeaways

An abstract structure or training of an artificial neural network without at least implicitly stating a specific use case is considered as non-technical.

The invention

The application underlying the present decision mainly concerns an adaption of the connections between layers of a neural network. In detail, the application discloses a concept called “loose couplings” which reduces the number of connections between the nodes of the several layers of the neural network compared to conventional fully-connected architectures as illustrated by the dotted lines in  Fig. 2 as shown below (cf. paras. [0004] and [0008] of the application). The “loose couplings” are defined by a sparse parity-check matrix of an error correcting code such as a LDPC code, spatially-coupled code or pseudo-cyclic code (cf. para. [0031] of the application).

Fig. 2 of EP 3089081 A1

Here is how the invention is defined in claim 1 of the main request:

  • Claim 1 (Main Request)

Is it technical?

Both the Board in charge and the Appellant agreed that claim 1 distinguishes itself from the closest prior art by means of the “loose couplings” as defined by the feature:

neural network being formed by loose couplings between the nodes in accordance with a sparse parity-check matrix of an error correcting code, wherein the error correcting code is a LDPC code, spatially-coupled code or pseudo-cyclic code

The Appellant’s arguments may be structured as follows:

A first argument of the Appellant addressed the achieved effects “within a computer” due to the provided architecture and stated that:

Machine learning serves a technical purpose by solving a well defined technical problem by mathematical means.

In order to support this statement, the Appellant referred to decision T 1326/06 from which the Appellant followed:

methods relating to data encoding and/or decoding can serve a technical purpose even though they are almost entirely based on mathematical algorithms and used for encrypting and decoding abstract data.

Accordingly, the Appellant argued that:

the possibility that the neural network apparatus may process, unknown, possibly abstract data in- and outputs should not necessarily take away the technical character of the distinguishing feature,

and supported this statement by referring to T 0697/17 according to which describing a technical feature at a high level of abstraction does not necessarily take away the feature’s technical character.

Therefore, the Appellant argued that the technical problem of improving the learning capability and efficiency of a machine is solved by reducing the required computational resources and preventing overfitting.

A second argument of the Appellant addressed the neural network as an automation tool:

The Appellant argued that:

an artificial neural network was a mathematical algorithm meant to mimic the human brain, by replicating biological optimization. It was implemented and trained in hardware, on a computer … It allowed the automation of complex tasks, so that the computer could perform them instead of a human.

With automation being generally recognized by the case law as a technical problem, the Appellant concluded that a neural network is not an abstract mathematical method, but instead uses mathematics to solve a technical problem. Accordingly, the present application would contribute to said domain by providing a new network structure allowing for a more efficient implementation by reducing computing and storage requirements.

However, the Board did not follow these arguments:

Regarding the allegedly achieved effects “within the computer”, the Board stated that:

while the storage and computation requirements are indeed reduced in comparison with the fully-connected network, this does not in and by itself translate to a technical effect, for the simple reason that the modified network is different and will not learn in the same way [as the fully-connected network]. So it requires less storage, but it does not do the same thing.”

The Board also provided an example in which they outline:

For instance, a one-neuron neural network requires the least storage, but it will not be able to learn any complex data relationship.

Therefore, the Board followed that:

the proposed comparison is incomplete, as it only focuses on the computational requirements.

Regarding the neural network as an automation tool, the Board stated that;

[it] sees no evidence that a neural network functions like a human brain. While its structure is inspired by that of the human brain, this does not imply that they can actually function like one.

A general “brain automation problem” can thus not be considered as solved by claim 1. In addition, as claim 1 does not further specify any particular task (i.e., the type of relationship to be learned), claim 1 does also not solve a corresponding automation problem.

As a result, the Board concluded that the claim as a whole merely specifies abstract computer-implemented mathematical operations on unspecified data. Accordingly, it’s subject-matter cannot be said to solve any technical problem and thus does not go beyond a mathematical method in the sense of Article 52 (2) EPC, which is implemented on a computer.

Therefore, the Board dismissed the appeal due to lack of inventive step.

More information

You can read the whole decision here: T 0702/20 (Sparsely connected neural network/MITSUBISHI) of November 7, 2022

Stay in the loop

Never miss a beat by subscribing to the email newsletter. Please see our Privacy Policy.

Privacy policy *
* = Required field

Please share this article if you enjoyed it!