Regarding inventions, the author (1) categorizes into physical-object inventions (e.g. mechanical ones) and material inventions (e.g. chemical ones), focusing on their appearances and properties; and (2) analyzes the formation process of inventions, focusing on the conception based on a principle and the establishment of a model, especially in the case of the invention by experiments, focusing on experimental results (experimental conditions, reproducible phenomena and products having an effect, which appear integrated). The author introduces the idea of "tentative principle" (that is presumed to be most correct in conducting the experiment). On the basis of the above understandings, the author suggests the way of the recognition of an inventor/joint inventors and the calculation of the contribution ratio of the joint inventors. Besides that, the author clarifies the necessity to use a Product-by-Process (PBP) claim, especially in the case of the material invention formed by the experiments, and conversely, set requirements for admitting a PBP claim. Furthermore, the identification of a product and the identity of products in PBP claims are also considered.