I am quite interested in moduli spaces for Rings and Ideals, a letter from Deligne to Bhargava is cited in Melanie Wood's thesis *Moduli spaces for Rings and Ideals* ([pdf](https://math.berkeley.edu/%7Emmwood/Publications/WoodthesisFinal.pdf)), studying the minimal free resolution of $n$ points in $\mathbb P^{n−2}$. It's also cited in the thesis of Kevin H. Wilson, *Three perspectives on $n$ points in $\mathbb{P}^{n-2}$* ([link](http://arks.princeton.edu/ark:/88435/dsp018k71nh131)) (after Theorem 135):



> 
> Such strong canonicity in these multiplicative structures has been implicitly used by many authors. For instance, Wright and Yukie [116] implicitly used this structure to parameterize rank $n$ rings over $\mathbb{Q}$. And Bhargava also implicitly relied on a much stronger
> canonicity (over $\mathbb{Z}$) in structuring his Higher Composition Laws [9, 10, 11, 14]. Perhaps the place where the idea of using such canonical multiplicative structures was first developed was in Deligne’s letter to Bhargava [41] which inspired Wood’s vast generalization in her thesis
> [114, 113, 112] extending Bhargava’s quadratic, cubic, and quartic Higher Composition Laws to arbitrary base schemes.
> 
> 
> 


Where can I find a copy of this letter (or a short explanation of the idea)? Thank you very much.



Deligne's letter to Bhargava from March 2004
The letter is [here](http://people.math.harvard.edu/%7Emmwood/DeligneToBhargava2004.pdf). Thanks to Will Sawin for alerting me to this request.


