Progress on Strassen's Conjecture
summary
Strassen's conjecture for symmetric tensors is advanced by proving additivity for forms that are linearly computable, using apolar methods: compute f⊥, choose an ideal generated by linear forms and evaluate the quotient f⊥:I+(l) to get a concrete lower bound. Monomial rank is computed by an explicit formula and coprime monomials in disjoint variables are additive (examples give ranks 12 and 4, sum 16 or 12+12=24 in variations). The approach uses the Landsberg–Teitler singularity bound, succeeds for many reducible and binary cases, and also identifies cubic examples where the linear method provably fails.
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chapters (20)
- 0:00Introduction
- 0:20Matrix multiplication context
- 1:04Tensors and elementary operations
- 2:26Strassen's breakthrough
- 4:04Significance of the result
- 6:05The conjecture explained
- 8:04Formalizing the conjecture
- 9:54Truth and border rank
- 11:24Symmetric tensor conjecture
- 12:57Difficulties in computation
- 13:53Lower bound approaches
- 15:24Polarity theory basics
- 17:31Landsberg-Titler technique
- 19:37Algebraic approach
- 22:12Monomial case study
- 24:08Linear computability
- 28:31Proving the conjecture
- 32:50Examples of computable forms
- 38:41Non-computable examples
- 46:04Final discussion and wrap-up
