If it's of interest, there's an account of fairly recent work in the "Strassen reloaded" paper https://dl.acm.org/doi/10.5555/3014904.3014983 https://dl.acm.org

If it's of interest, there's an account of fairly recent work in the "Strassen reloaded" paper https://dl.acm.org/doi/10.5555/3014904.3014983 https://dl.acm.org/doi/10.5555/3014904.3014983 or otherwise in https://www.cs.utexas.edu/users/flame/pubs/FLAWN79.pdf https://www.cs.utexas.edu/users/flame/pubs/FLAWN79.pdf