Automated proving in planar geometry based on the complex number identity method and elimination
This work provides an incremental improvement for automated theorem proving in geometry, targeting researchers and educators in computational mathematics.
The authors tackled the problem of automating proofs in planar geometry by improving the complex number identity method with elimination ideals, resulting in a fully automated procedure implemented in multiple computer algebra systems and a prototype in GeoGebra.
We improve the complex number identity proving method to a fully automated procedure, based on elimination ideals. By using declarative equations or rewriting each real-relational hypothesis $h_i$ to $h_i-r_i$, and the thesis $t$ to $t-r$, clearing the denominators and introducing an extra expression with a slack variable, we eliminate all free and relational point variables. From the obtained ideal $I$ in $\mathbb{Q}[r,r_1,r_2,\ldots]$ we can find a conclusive result. It plays an important role that if $r_1,r_2,\ldots$ are real, $r$ must also be real if there is a linear polynomial $p(r)\in I$, unless division by zero occurs when expressing $r$. Our results are presented in Mathematica, Maple and in a new version of the Giac computer algebra system. Finally, we present a prototype of the automated procedure in an experimental version of the dynamic geometry software GeoGebra.