Part 1/2
Square matrices that are singular at limit (LP), branch (BP), and Hopf points, and their determinants as test functions (00:00)
Nonsingular bordering of singular matrices with rank drop 1 (29:00)
Test function for a singularity (36:23)
Part 2/2
Derivative of the test function for a singularity (12:40)
Regularity of the test function for LP (12:40)
Regularity of the test function for BP (19:00)