Gerstenhaber bracket ($[f,g]$)

Write $f\circ g={\sum }_{i=0}^{p-1}(-1{)}^{i(q-1)}f{\circ }_{i}g$ for insertion of a degree-$q$ cochain into a degree-$p$ one. With the unsigned Hochschild cup product and the left graded Leibniz rule, take $[f,g]=(-1{)}^{(p-1)(q-1)}f\circ g-g\circ f$. It descends to Hochschild cohomology and gives a Gerstenhaber algebra. The alternative insertion bracket $f\circ g-(-1{)}^{(p-1)(q-1)}g\circ f$ differs by the displayed degree sign and obeys the corresponding right rule. Degree-one brackets are commutators of derivations in either convention.