A depth-4 algebraic circuit with top fan-in $k$ and bottom fan-in $2$ is a circuit $\Phi$ of the form $\Phi = \sum_{i=1}^k \prod_{j=1}^{m_i} Q_{ij}$, where the polynomials $Q_{ij} \in \mathbb{K}[x_1, \ldots, x_n]$ have degree at most $2$.
The class of all such circuits is denoted by $\Sigma^k \Pi \Sigma ... more >>>

For a Boolean function $f:\{0,1\}^n\to\{0,1\}$, the higher-order Boolean derivative $D_S f$ computes the parity of $f$ over each $S$-dimensional subcube. We prove that $D_S f\equiv 1$ exactly when $S$ is a maximal monomial support in the algebraic normal form of $f$. This correspondence motivates the derivative certificate depth $\Delta_\partial(f)$, defined ... more >>>

The hardness vs. randomness paradigm converts a function $f \colon \{0,1\}^n \rightarrow \{0,1\}$ that is hard for circuits of size $s$ into a pseudorandom generator (PRG) $G \colon \{0,1\}^d \to \{0,1\}^{s'}$ that fools circuits of size $s' = s'(s)$. In the application for derandomization, such as proofs of $\mathbf{BPP} = ... more >>>