Q1. What is the "problem solution approach"? Q2. What are the differences between a "patent" and a "utility model"? Q3. What is the definition of the "person skilled in the art"? Q4. What are the definitions of the "clarity, unity and sufficiency"? CASE: BOTTLE STOPPERS Client Letter The present invention relates to stoppers for wine bottles. Bottle stoppers for wine bottles comprising a body made of cork are known. An exchange of gasses between the interior of the bottle and the exterior of the bottle is necessary for the wine to mature. A drawback with the known stoppers is that the gas permeability of the cork varies greatly depending on the tree from which it was sourced. The bottle stopper 10 of FIG. 1 comprises a body 2 . The body 2 is made of synthetic rubber. The synthetic rubber is impermeable to liquid and gas. The bottle stopper 10 further comprises a narrow air channel 3, which extends through the body 2. When the stopper closes the neck of a bottle, gasses can flow through the air channel between the interior and the exterior of the bottle. Because the air channel 3 is very narrow, liquid cannot flow through it. The optimal rate of exchange of gasses for maturing a specific wine can be achieved by selecting a stopper 10 having an air channel 3 of an appropriate diameter. Prior Art Documents Document D1 FIG. shows a stopper 100 for closing a bottle, with one half cut away. The stopper 100 is made of cork. Cork is provided from layers of bark of cork oak trees. Cork is a material with a randomly distributed, continuous network of interconnected air channels running through the material. The material itself is impermeable to liquids and to gasses such as air. However, gasses can flow through the interconnected air channels. Thus, a stopper made of cork is impermeable to liquids, but permeable to gasses such as air. Document D2 FIG. shows a stopper 400 with part cut away. It comprises a body 402 made of synthetic rubber foam and a filter plate 404 . The filter plate 404 is glued onto a first planar surface of the body 402 . The filter plate 404 is made of an aluminium foil with perforations forming micro air channels. The filter plate 404 prevents wine from coming into contact with the synthetic rubber foam. When the stopper closes the neck of a bottle, the filter plate 404 is located inside the bottle. Gasses can flow between the inside and the outside of the bottle via the micro air channels in the filter plate 404 and the air channels in the body 402. Q5. Write a novel and an inventive independent claim with the widest protection scope according to the invention described in the client letter and the prior arts documents. Q6. Explain why the independent claim you have written in the 5 th question is novel over D1 and D2. Q7. Explain why the independent claim you have written in the 5 th question is inventive over D1 and D2, using the problem solution approach