Exact expanded PA statement
forall a b c d. (a * b) * (c * d) = (a * c) * (b * d)Structural proof guide
Four factors may exchange their two middle entries.
Direct prerequisites: mul_assoc, mul_comm. The authored body proceeds by direct introduction and elimination.
Proof neighborhood
Direct dependencies
Direct dependents
Formal native tactic body
Dependencies are hypotheses of this body receipt. The focused endpoint audits separately check the complete empty-context certificates.
- 0001
intro a - 0002
intro b - 0003
intro c - 0004
intro d - 0005
trans a * (b * (c * d)) - 0006
apply mul_assoc - 0007
trans a * ((b * c) * d) - 0008
congr - 0009
refl - 0010
symm - 0011
apply mul_assoc - 0012
trans a * ((c * b) * d) - 0013
congr - 0014
refl - 0015
congr - 0016
apply mul_comm - 0017
refl - 0018
trans a * (c * (b * d)) - 0019
congr - 0020
refl - 0021
apply mul_assoc - 0022
symm - 0023
apply mul_assoc