On: A Spectre Is Haunting Unicode (2018)

[runarberg]

I have also seen

- ℙ used to denote a probability distribution

- 𝔼[X] as the expected value of a random variable X

- 𝟙_S as an indicator function for a set S (which is denoted as a subscript)

- 𝕕 as the differential and integral operator denouncing which variable to integrate over 𝕕f/𝕕x f(x) or ∫ f(x) 𝕕x

[OscarCunningham → runarberg]

I've also seen 𝔸 for affine space, 𝔹 for the Booleans, 𝔽 for a field, 𝕂 for a field, 𝕆 for octonions and 𝕊 for surreals.

I think I've seen 𝕀 and 𝕚 for identity matrices and suchlike, and I'm sure 𝟘 also gets some use.