terms by 'if-then' statements. For example, when two input variables (validation metrics) are aggregated four rules are required, formalized as: PREMISECONCLUSION if x1 is F and x2 is F then yi is B1 if x1 is F and x2 is U then y2 is B2 if x1 is U and x2 is F then y3 is B3 if x1 is U and x2 is U then y4 is B4 where xi is an input variable, yi is an output variable and Bi is a conclusion (or expert weight). The value of each conjunction (… and …) is the minimum of the quantified fuzzy groups, which are obtained from complementary S-shaped distribution curves. The output fuzzy sets for all the rules are then aggregated into a single fuzzy set. This group encompasses a range of output values, and is de-fuzzified in order to resolve a single crisp output value from the group (i.e. a value between 0 and 1). This approach uses the centroid method to obtain the representative non-fuzzy value for the output, as commonly adopted in the Sugeno-type systems. The expert reasoning runs as follows: if all input variables are F, the value of the module is 0 (good response according to all metrics used); if all indices are U, the value of the module is 1 (bad response according to all inputs used), while all the other combinations assume intermediate values. Limits F and U may come from experience, may be extracted from literature, or may be set by law. The weights can be chosen based on the analyst own experience in handling each input. Authorship (selected) See a full bibliography on Bellocchi's web site . Fuzzy logic and validation Bellocchi G., Rivington M., Matthews K., Acutis M., 2015. Deliberative processes for comprehensive evaluation of agroecological models. A review. Agronomy for Sustainable Development, 35, 589-605. Alexandrov G.A., Ames G., Bellocchi G., Bruen M., Crout N., Erechtchoukova M., Hildebrandt A., Hoffman F., Jackisch C., Khaiter P., Mannina G., Matsunaga T., Purucker S.T., Rivington M., Samaniego L., 2011. Technical assessment and evaluation of environmental models and software: Letter to the Editor. Environmental Modelling and Software, 26, 328-336. Bellocchi G., De Giacomo M., Fori N., Mazzara M., Palmaccio E., Savini C., Di Domenicantonio C., Onori R., van den Eede G., 2010. Testing the interaction between analytical modules: an examples with Roundup Ready soybean line GTS 40-3-2. BMC Biotechnology, 10:55 . Bellocchi