mathlib

540b766a - feat(tactic/linear_combination): allow `linear_combination with { exponent := n }` (#15428)

feat(tactic/linear_combination): allow `linear_combination with { exponent := n }` (#15428) #15425 will solve problems where the goal is not a linear combination of hypotheses, but a *power* of the goal is. This PR provides a more natural certificate for these proofs. Writing `linear_combination ... with { exponent := 2 }` will square the goal before subtracting the linear combination. In principle this could be useful even outside of `polyrith`. Co-authored-by: Rob Lewis <rob.y.lewis@gmail.com> Co-authored-by: Yaël Dillies <yael.dillies@gmail.com>