Notes on Selection Rules of Canonical Differential Equations and Relative Cohomology

We give an explanation of the dlog-form of the coefficient matrix of canonical differential equations using the projection of (n+1)-dlog forms onto n-dlog forms. This projection is done using the leading-order formula for intersection numbers. This formula gives a simple way to compute the coefficient matrix. When combined with the relative twisted cohomology, redundancy in computation using the regulator method can be avoided.