In the above, we provide a long version of our submission, namely SIGIR2020_Long_Version.pdf, where we include all formal proofs of the theorems and lemmas, and more illustrative examples that give insights into the ideas and usage of the inference rules presented in our submission. We highly recommend the readers to refer to this version for a better understanding of the materials and our contributions of this work. The long version can be downloaded by right clicking on it and saving it somewhere locally on your computer, or by clicking the green button "Clone or download" as a zip file, together with the source code for our forgetting prototype.