Tag: 3.5.01

Spam classification/MICROSOFT – T 0022/ 12 – 16 November 2015

This decision was particularly concerned with whether a technical effect exists with a certain classification of emails.

Object of the Invention:

  • the invention concerns the classification of emails, e.g. as either spam or legitimate mail
  • an incoming email is first analysed to determine whether it contains one or more features in a set of predetermined features that are particularly characteristic of spam
  • two types of feature are used: word-oriented and “handcrafted“
  • the former refers to the presence of particular words, or stems of words, the latter to features determined through human judgement alone
  • examples of a handcrafted feature is a sender address, since most spam messages are sent at night from “.com” or “.net” domains

Board I (inventive step):

  • the Board agrees with the Examining Division that the classification of messages as a function of their content is not technical per se
  • it is immaterial whether the messages are electronic messages, because, even though an email has technical properties, it is the content of the email that is classified
  • mathematical methods as such are not technical and the application of a mathematical method as such in a non-technical analysis of message content does not change that
  • if there is a technical effect, it can only reside in the automation of the email classification using a computer
  • the technicality of the computer is not enough to establish a technical effect of any method that it executes

Appellant I (inventive step):

  • a classification based on a combination of “handcrafted features” and “word oriented features” had the technical effect of reducing processing load

Board II (inventive step):

  • the Board is not persuaded that the alleged effect is actually achieved by the invention
  • there is no link between the word-oriented and handcrafted features, so that the latter reduces the processing involved in the former
  • the handcrafted features are, rather, a different class of features that the user considers indicative of spam, but which cannot be expressed in terms of the presence of individual words
  • simply adding a second class of features to the analysis increases the load rather than reducing it
  • furthermore, the Board does not consider that the de-automation of a computer-implemented method, by making a human perform steps that a computer could do automatically, is a technical solution to a technical problem
  • any reduction in computer processing would be a mere consequence of the de-automation
  • handcrafted features relate to information content that is considered as indicative of spam
  • including such features in the analysis might, if well chosen, improve the quality of the classification, but the designation of a second class of features does not provide a technical effect

Appellant II (inventive step):

  • the appellant argued, however, that there was a technical effect in the particular combination of an SVM and a sigmoid function
  • performing the method in two stages, first using an SVM, and then applying an adjustable sigmoid function as a threshold to the output of the SVM, reduced the processing load, which reduced the complexity of the computer implementation
  • thus, the invention was motivated by technical considerations of the computer implementation

Board III (inventive step):

  • the Board is not persuaded by the appellant’s arguments on this point
  • the Board does not find support, anywhere in the application, for the classifier being updated by adjusting the sigmoid parameters alone, without retraining the SVM
  • the generation of parameters for the classifier during the training phase involves two steps:
    • first the weight vector w is determined by conventional SVM training methods
    • second the optimal sigmoid parameters are calculated by using a maximum likelihood on the training data
  • there is nothing to suggest that re-training may involve only one of those steps, or that the classifier may be updated by simply adjusting the parameters A and B
  • on the contrary, it is the teaching of the application that, when the conditions of what is considered as spam change (e.g. when the user reclassifies a message) the whole classifier is retrained
  • furthermore, the Board does not consider that reducing the complexity of an algorithm is necessarily a technical effect, or evidence of underlying technical considerations
  • that is because complexity is an inherent property of the algorithm as such
  • if the design of the algorithm were motivated by a problem related to the internal workings of the computer, e.g. if it were adapted to a particular computer architecture, it could, arguably, be considered as technical (T 1358/09 referring to T 258/03)
  • however, the Board does not see any such motivations in the present case
  • thus, the Board is not persuaded that the use of an SVM in combination with a sigmoid threshold function contributes, technically, to the the computer implementation
  • the Board rather considers this to be a mathematical method
  • the technical implementation of the method consists in programming the computer to perform the method steps
  • this would have been a routine task for the skilled programmer
  • –> no inventive step

Classification method/COMPTEL – T 1784/06 – 21 September 2012

In this decision, the appellant criticises the COMVIK approach on several points. The Board disagrees. With regard to inventive step, according to the Board, there is a lack of “technical purpose” according to T1227/05.

Information from the author: “technical purpose” is no longer sufficient according to decision G1/19 for non-technical features to make a technical contribution. According to current case law (as of August 2024), in such a case a further or intended or implied technical use is required.

Object of the Invention:

  • data records, e. g. the duration and data volume of a telecommunication connection, that are sorted into service classes, in particular for rating and billing purposes
  • identifying the class of a service from a data record forms a performance bottleneck once the number of services is increased to the thousands
  • the application seeks to provide a method which can handle large numbers of service classes more efficiently than the conventional use of conditional statements does
  • the solution is based on reducing, as a first step, a large number of service classes into specific sets
  • these sets are then intersected in a final step
  • this algorithm classifies data records more efficiently

Board (COMVIK approach):

  • it would appear paradoxical to the Board to recognise an inventive step on the basis of a non-technical innovation (such as an organisational, administrative, commercial or mathematical algorithm) having no technical implication other than the (obvious) desire for its implementation on a general-purpose computer

Appellant I (COMVIK approach):

  • claimed subject-matter as a whole should be examined for the presence of an inventive step once the subject-matter as a whole has been found to meet the technology criterion of Article 52(1)(2)(3) EPC
  • Article 56 EPC 1973 should be applied independently of Article 52(1)(2)(3) EPC because Article 52(2) EPC has to be applied independently of Article 56 EPC 1973

Board I (COMVIK approach):

  • the Board does not accept such formal reasoning and points out that it is normal and often necessary for legal provisions to be in an asymmetric relationship or hierarchical dependency
  • for example, the novelty of a claim has to be examined independently of inventive step considerations, whereas a finding of inventiveness presupposes a novelty examination
  • another example is the validity of a priority claim which has to be checked independently of novelty and inventive step requirements, whereas novelty and inventive step cannot be established independently of the validity of a priority right.

Appellant II (COMVIK approach):

  • regarding the Board’s insistence on a technical problem when applying the problem-and-solution approach, the appellant disputes that such a requirement can be deduced from the EPC or introduced from its Implementing Regulations
  • the appellant refers inter alia to decision T 473/08 (by a different Board) to point out that “a non-technical problem can have a technical solution“

Board II (COMVIK approach):

  • there is no divergence, the Board agrees to the statement that a non-technical problem can have a technical solution
  • on the other hand, where an intrinsically non-technical solution (mathematical algorithm) seeks to derive a technical character from the problem solved, the problem must be technical
  • this is the point on which the present case hinges

Appellant III (COMVIK approach):

  • another argument of the appellant refers to the legislative history of the EPC (travaux préparatoires) which is said not to provide any explicit support for a cumulative application of Article 52(2) EPC and Article 56 EPC 1973

Board III (COMVIK approach):

  • the restriction of substantive patent law to technical subject-matter is so self-evident that the founding fathers of the EPC did not even mention that requirement in the original (1973) version of Article 52(1)
  • the explicit clause “in all fields of technology” was not added to Article 52(1) until the Diplomatic Conference in the year 2000 harmonised the Article with the TRIPs treaty
  • nevertheless, Article 52(1) EPC has always been understood as referring to technical inventions

Board IV (inventive step):

  • as the algorithm is a mathematical (inter alia Boolean) method and mathematical methods as such are deemed to be non-inventions (Article 52(2)(3) EPC), a technical character of the algorithm could be recognised only if it served a technical purpose (T1227/05)
  • however, the automatic classification of data records according to claim 1 serves only the purpose of classifying the data records, without implying any technical use of the classification
  • the claim covers any non-technical (e.g. administrative or commercial) use of the classified data records
  • in the light of the description, the classification method prepares rating and billing procedures
  • the Board does not consider the result of the algorithm — a set of classified data records — as technical

Board V (inventive step):

  • enhanced speed of an algorithm, as compared to other algorithms, is not sufficient to establish a technical character of the algorithm (T 1227/05)
  • if a computer-implemented algorithm runs more quickly, the resulting saving in energy is a technical effect inherent to the normal interaction of software and hardware, i.e. it is not a “further” technical effect of the algorithmic program controlling the computer (T 1173/97)
  • the claimed algorithm may allow a data record to be processed in a parallel computer architecture as the various fields of a data record can be judged separately in a first level of processing
  • however, claim 1 is not limited to an implementation on a parallel hardware structure
  • in fact, the application as a whole is silent on parallel data processing (Parallel processing has been mentioned by the decision under appeal and addressed by the statement setting out the grounds of appeal)
  • –> no inventive step

Edge Detection – T 0165/ 12 – 6 July 2017

In this decision, the Board found that the description of the main request did not support the claim, as the description disclosed only one specific example of a merely general feature (“first phase congruency component”). In an auxiliary request, the appellant overcame this rejection, but the claimed subject-matter is still considered not to be inventive

Object of the Invention:

  • method for edge detection of an image
  • the method categorises pixels in the image as edge pixels or non-edge pixels

Board I (support by the description – main request):

  • in the application itself, no different way to determine the phase congruency at a pixel is disclosed than to calculate the ratio between the local energy at the pixel and the sum of Fourier components
  • also in the statement of grounds the appellant provided no additional example and, thus, failed to support its view that a different phase congruency component could be used
  • hence, it is a mere allegation that other “first phase congruency components” could be used
  • according to the established jurisprudence of the boards of appeal, the requirement of 84 EPC means that the subject-matter of the claim must be taken from the description and it is not admissible to claim something that is not described
  • in decision T 94/05, in particular, the board pointed out that the requirement for the claims to be supported by the description was intended to ensure that the extent of protection as defined by the patent claims corresponds to the technical contribution of the disclosed invention to the art
  • therefore the claims must reflect the actual contribution to the art in such a way that the skilled person is able to perform the invention in the entire range claimed
  • the skilled person, at least after reading the patent specification, taking account of his common general knowledge, and possibly also after carrying out normal experiments, must actually be provided with at least a plurality of different embodiment variants
  • in the present case, the use of the term “first phase congruence component” leaves it open, what other embodiments besides the “local energy” are envisaged
  • –> there is not enough support in the description for using the broad term “first phase congruency component” in the independent claims instead of the only embodiment disclosed in the specification, i.e. the “local energy”

Board II (inventive step – auxiliary request):

  • technical effect disclosed in the application is: “This allows for pixels that fail the phase congruency test, to be counted as edge pixels if their local energy satisfies the phase congruency component criteria.“
  • a person skilled in the art recognizing that a first method for edge detection does not result in an expected number of edge pixels evidently has three straightforward possibilities to increase the number of edge pixels:
    1. by using another – better – method for edge detection
    2. by adapting the first method for edge detection (for instance by reducing a respective threshold that distinguishes between non-edge pixels and edge pixels)
    3. by using a further known method for edge detection, which provides different results (i.e. additional edge pixels) than the first method and combining the results of both methods
  • for instance, an example for an algorithm using different methods for detecting different kind of edges is disclosed in D3
  • choosing one out of these straightforward possibilities does not involve an inventive step
  • the Board does not see an inventive step in using the local energy method for finding additional edge pixels that were missed by the first method (as claimed) as compared to rejecting edge pixels by using the local energy method that were found by the first method, but should not be considered as edge pixels (as disclosed in D1)
  • this is considered a mere implementation detail, depending on the choice of criteria of the first method, which might cause too many or not enough edge pixels

Categorization of Messages – T 1316/09 – 18 December 2012

In this decision, the Board does not see any technical effect with respect to the distinguishing features of the claimed subject-matter over the prior art.

Object of the Invention:

  • method and a system for suggesting automated responses to an incoming electronic message based on content analysis and categorisation

Board I (inventive step):

  • a decisive factor in any assessment of inventive step is the objective technical problem underlying the invention
  • the inventive solution of the objective technical problem must be based on the technical features of the invention as claimed
  • text classification per se, however, does not serve any technical purpose
  • neither does the combination of different methods of text categorisation per se provide any relevant technical effect that could form a valid basis for defining the objective technical problem
  • in the light of document D2, the invention seems merely to consist of proposing an alternative to the classifier 34 in the form of a “classifier committee” combining the rule-based scheme of D1 with an example-based classifier based on the k-nn algorithm disclosed in D1

Appellant (inventive step):

  • the distinguishing features of claim 1 over D2 lead to the following technical effects:
    • more relevant responses to an incoming message can be located, i.e. a greater number of irrelevant responses are filtered out
    • the time and effort required to respond to incoming messages is reduced
    • messages can be processed at a greater rate, i.e. more efficiently
    • the quality of responses to messages can be improved
    • the synergistic combination of query based classification and example based classification yields greater efficiency and better results than either method taken alone
  • the skilled person is confronted with the objective technical problem of how to more efficiently and effectively provide a response to an incoming message

Board II (inventive step):

  • the alleged effects are speculative, considering that nothing in the claimed invention prevents the intersection of the categories provided by a query and by the example-based algorithm being empty and hence that the claimed method is a complete failure
  • even more importantly, the appellant did not provide any substantive reason why a more efficient and better categorisation of the informational content of an incoming electronic message qualifies as a technical effect at all and why such an advancement over the prior art has technical character
  • no inventive step

Text mining/BOEING – T 1416/06 – 24 April 2009

In this decision the board considers the data does not form a physical entity.

Object of the Invention:

  • the subject matter is directed to a method of representing a document collection
  • the method is to a large extent defined in terms of equations
  • the purpose of the method is to present the information in a way that can be more easily understood or evaluated by a user

Board I (field of technology):

  • at the bottom of the method is a mathematical technique known as orthogonal decomposition
  • this technique is generally applied to large matrices and, like many mathematical functions, can be represented graphically
  • it is typical for mathematical representations that they involve pure numbers, ie abstract data, having no physical connotation
  • in the present invention the representations are of documents and the terms used in the documents
  • thus, although the data have a certain “meaning“, they remain abstract
  • they can hardly be regarded as forming a physical entity, nor does the method result in a change in the data but merely in their representation (T 208/84)
  • it could therefore be argued that the invention – apart from its implementation – is essentially a mathematical method pursuant to Article 52(2)(a) EPC, resulting in a presentation of information pursuant to Article 52(2)(d) EPC

Image classification / STMICROELECTRONICS – T 1148/05 – 27 May 2009

In this decision, a method of image classification was claimed. The Board assumed that all features contribute to the technical character and that the sufficiency of disclosure was given.

Object of the Invention:

  • image classification method for classifying digital images into photographs, texts, and graphics
  • conventional heuristic methods implemented by expert systems present a number of drawbacks, in particular the computational complexity required for analysing the large number of pixels of an image
  • another problem is touched on by the “impossibility of optimising analysis using parallel architectures”
  • the thrust of the application is for constructing a classification algorithm (“tree-structured classifier”) which is both powerful in terms of class discrimination and efficient in terms of processing speed

Board I (sufficiency of disclosure (Article 83 EPC):

  • examining division has argued that the application does not disclose any specific example of a tree classifier adapted to a specific set of image classes
  • however, the application does disclose the “high-level classification problem” (i.e. to distinguish photographs from graphics and texts, see paragraphs 0002 and 0046) and it discloses that 72 lowlevel features have been chosen (from among 389 features, for example, see paragraphs 0016 and 0052) to carry out the test described in paragraphs 0047 to 0053
  • background of that choice may lack detail but it still provides the general teaching that a (sub-)set of low-level features can be chosen according to general criteria (discrimination power and efficiency, column 3, lines 22 to 25) and managed in any combination (paragraph 0020) to build a classifier fulfilling a set of conditions (see e.g. paragraphs 0021/0022, 0039, 0042)

Board II (inventive step):

  • all features are assumed to contribute to the technical character of the claimed subject matter
  • general aspects of processing and pre-classifying digital images are old
  • however, the claimed method derives novelty from the use of a large library of 22 specific technical image parameters (low-level features) which are not disclosed in combination in any of the available prior art documents
  • Article 56 EPC 1973 asks for an inventive technical contribution (T 641/00-Two identities/COMVIK)
  • the following line of argument guides the skilled person in an obvious manner from the prior art to the claimed method:
    • classification of digital images for the adoption of the most suitable image-processing strategies has become “an indispensable need“, see application
    • according to D2, which may be used as a starting point, Web images are classified into photographs and graphics
    • in digital image processing, it is well-known (and inevitable) to construct a classification algorithm before it is used for classifying images
    • when constructing an algorithm for classifying digital images, it is well-known to accomplish this by way of a tree classifier using features or parameters which describe a digital image, see e.g. the prior art referred to in the application itself
    • invention mainly differs from prior art by the library of specific low-level features for improving the classification result
    • however, it is evident that all the image features which are known to describe properties of digital images are natural candidates for distinguishing images and classes of images, from each other
    • the skilled person has an expectation of improvement in that any low-level feature is prima facie suitable for discriminating image classes at least at a high level.
    • the skilled person designing a binary classification tree obviously prefers features having a great power of discriminating two classes (see e.g. D3, page 4, second paragraph)
    • the application itself presents most of its low-level features as forming part of the prior art
    • regarding the few features for which no prior art has been cited in the application, the application still conveys the impression that those features represent usual parameters for describing and analysing digital images
    • otherwise, if they were fundamentally new to the image processing person, they would have to be disclosed in much greater detail
    • –> no inventive step

Translating natural languages/SYSTRAN – T 1177/97 – 9 July 2002

This decision concerns the technical nature of information. This can have a technical character if:

– it is used in or intended for use in a technical system,

– if it reflects the properties of the technical system.

Object of the Invention:

  • automatic search in dictionaries with a character-by-character process that cuts off the characters from the end of the word until a valid combination of stem and ending is found to achieve the longest match
  • Claim 1 differs from the closest prior art (general purpose computer) in that it comprises a low frequency dictionary look-up process on the basis of the socalled “longest match principle“, meaning a look-up process which produces the dictionary entry with the longest stem matching the source text word

Board I (inventive step)

  • a piece of information in a technical system, or its usability for this purpose, may confer a technical character on the information itself in that it reflects the properties of the technical system, for instance by being specifically formatted and/or processed
  • such information when used in or processed by the technical system may be part of a technical solution to a technical problem and form the basis for a technical contribution of the invention to the prior art

Board II (inventive step)

  • the use of a low frequency dictionary and an algorithm of sequentially dropping letters as part of the matching process may be regarded as the result of a specific adaptation of the translation process for computer implementation à in principle as technical components of the claimed invention
  • the application of the “longest match principle” is in substance based on linguistic considerations
  • applying the principles laid down by the Board in its COMVIK-decision, the decision for one or the other matching principle (“longest match principle”, “shortest-matching method”) does not seem to solve any technical problem and hence does not fall within the responsibility of a technically skilled person
  • it is rather a non-technical constraint determined by the linguistic expert and given to the skilled person as part of the framework of his task, namely implementing the known low frequency dictionary look-up process by applying the “longest match principle”

Contrast enhancement/AGFA-GEVAERT – T 1019/99 – 16 June 2004

In this decision, the closest prior art is a document published about 5 years before the patent. According to the patentee, no one had worked on this document during those 5 years. In this decision, therefore, the competent Board is dealing with the question of whether an ‘old’ document can be used as the closest prior art.

Object of the Invention:

  • the patent concerns the problem of image contrast enhancement in a radiographic imaging system in which there is a large difference in dynamic range between the sensor and the imaging device
  • this is solved by decomposing the image into multiple detail images at different resolution levels (multi-scale decomposition) and filtering some resolution levels with a non-linear conversion function
  • Claim 1 differs from the closest prior art (general purpose computer) in that the non-linear conversion function is specified to be monotonically increasing, odd and to have a slope that gradually decreases with increasing argument values

Appellant (closest prior art – old document):

  • D2 cannot be taken as a starting point to arrive at the invention because, it is an isolated document that no one had worked on in the five years prior to the patent

Board (closest prior art – old document):

  • any document that is state of the art under Article 54(2) EPC may be a candidate for the closest prior art
  • the state of the art is everything made available to the public
  • the jurisprudence acknowledges, some cases where a document may not be a realistic starting point because it either relates to outdated technology, and/or is associated with such well known disadvantages that the skilled person would not even consider trying to improve on it
  • in the present case, the appellant is essentially offering an additional reason for not using D2, namely that it did not receive any attention after its publication
  • the Board does not judge that D2, published only five years before the priority date of the patent, in any way represents outdated technology, even in a fast moving area such as digital image processing
  • concerning the status of D2 as an isolated document, the Board agrees with the respondent that there may be various unknown technical or economic reasons preventing an otherwise promising approach from being adopted rapidly after its early publication

Character Recognition – T 135/92 – 15 May 1992

This decision concerns a method for image data. The competent chamber considers the object and solution to be technical.

Object of the Invention:

  • automatic scanning and identification of unknown characters (of image data)
  • in a first stage, different sets of logic tests are used for the identification of characters; were a character not to be identified by the said logic tests, the character would be tested in the second stage by logic tests which are discrete from the tests of the first stage

Board:

  • problem to be solved is to identify characters that could not be identified by the known system
  • this problem is clearly technical
  • solution is also of a technical character, as the addition of additional stages to a first stage clearly represents a technical measure

Stock index/NASDAQ – T 1161/04 – 6 December 2006

In this case, the responsible board decides in particular whether input data is functional data / a physical entity or simply cognitive data.

Object of the Invention:

  • Claim 1 relates to an apparatus for rebalancing a stock index
  • stock indexes are used to track the performance of a group of stocks
  • capitalization-weighted indexes are regarded as having the disadvantage that a few large stocks may dominate the overall performance of the index
  • the invention is aimed at overcoming this drawback by scaling down large individual stocks and distributing the corresponding excess capitalization over the smaller stocks
  • the output data of the apparatus correspond to the redistributed capitalization weights of the stock index.

Board I (inventive step):

  • the hardware defined in claim 1 is well known as such
  • the invention concerns the way data relating to stocks in a stock index are processed
  • the computer implementation of this process must be assumed to be straightforward

Appellant I (inventive step):

  • decisions T 115/85 and T 362/90 established the principle that automatic visual display of conditions prevailing or desirable in an apparatus or system was basically a technical problem

Board II (inventive step):

  • the invention in the case T 115/85 was a method for displaying one of a set of predetermined messages
  • each such message indicated a specific event which might occur in the input/output device of a text processing system
  • this system comprised a processor, a keyboard, a display and a memory and would also require means for detecting events
  • deciding board: “giving visual indications automatically about conditions prevailing in an apparatus or system is basically a technical problem”
  • the Board cannot agree with the appellants that the present invention relates to an “apparatus or system” in the way these terms are used in decision T 115/85
  • the data entering the system of claim 1 are “information relating to stocks”
  • this is information of a descriptive kind having exclusively “cognitive content” in the sense of decision T 1194/97
  • applying the test proposed in this decision for cognitive information as opposed to “functional data“, it can be seen that if stock information were lost the claimed apparatus would still function, ie still perform the algorithm and produce output data (although these data would be meaningless)
  • presentations of information having merely “cognitive content” are as such excluded from patentability under Article 52(2) EPC and cannot contribute to an inventive step
  • it appears necessary to point out that the nature of such information is irrelevant
  • a description of a gear box may intuitively appear more “technical” than a play by Shakespeare, but in fact both are examples of data having only cognitive content
  • the Board does not accept the appellants’ argument that the present invention provides visual indications automatically about conditions prevailing in a system in the sense of decision T 115/85 for the triple reason:
    • that the conditions are outside the claimed system,
    • that they are not detected by the claimed system but input to it in the form of descriptive data, and
    • that the system in which the conditions prevail is of a commercial rather than technical nature

Appellant II (inventive step):

  • the “information relating to stocks” in claim 1 represents physical entities and therefore has technical character.

Board III (inventive step):

  • in T 208/84 a distinction is made between abstract concepts on the one hand and technical processes involving and modifying a “physical entity”, such as an electrical signal, on the other hand
  • the present invention is not completely abstract since it involves electrical signals
  • but the mere fact that an invention involves signals representing data does not necessarily imply that it solves a technical problem going beyond that of physically representing these data
  • for example, information having only cognitive content is also conventionally represented by (electrical) signals
  • decision T 208/84 therefore requires that the data should represent not just numbers but a “physical entity“
  • the physical entity in that case was an image, and the invention aimed at restoring it if distorted
  • in the case T 1194/97 the physical entity was a synchronization signal
  • the data were thus in both cases “functional” because the degree of restoration of an image or the synchronisation state of a receiver are objectively measurable entities
  • in both cases a technical effect was achieved by the functional nature of the data irrespective of their cognitive contents
  • in the present case however the data represent nothing but numbers, arguably describing “physical entities“, which necessarily require interpretation by a human being without any further interaction with, or modification of, the technical system
  • the data input to the claimed apparatus have no technical function
  • the processing performed on them comprises classification, scaling and redistribution
  • these steps concern exclusively the cognitive content of the data (their numerical value)
  • this is pure information processing which is as such excluded as a mental act by virtue of Article 52(2) EPC
  • the technical task is reduced to the implementation of the process on a conventional computer, something which was obvious for the skilled person –> no inventive step