On the complexity of bounded-depth circuits and formulas over the basis of fan-in gates

We obtain estimates for the complexity of the implementation of n-place Boolean functions by circuits and formulas built of unbounded fan-in conjunction and disjunction gates and either negation gates or negations of variables as inputs. Restrictions on the depth of circuits and formulas are imposed. In a number of cases, the estimates obtained in the paper are shown to be asymptotically sharp. In particular, for the complexity of circuits with variables and their negations on inputs, the Shannon function is asymptotically estimated as $2\cdot {{2}^{n/2}};$this estimate is attained on depth-3 circuits.

On (Not) Computing the Möbius Function Using Bounded Depth Circuits

Any function F: {0,. . ., N − 1} → {−1,1} such that F(x) can be computed from the binary digits of x using a bounded depth circuit is orthogonal to the Möbius function μ in the sense that \[ \frac{1}{N} \sum_{0 \leq x \leq N-1} \mu(x)F(x) → 0 \quad\text{as}~~ N → \infty. \] The proof combines a result of Linial, Mansour and Nisan with techniques of Kátai and Harman, used in their work on finding primes with specified digits.

WEAKLY ITERATED BLOCK PRODUCTS AND APPLICATIONS TO LOGIC AND COMPLEXITY

Unlike the wreath product, the block product is not associative at the level of varieties. All decomposition theorems involving block products, such as the bilateral version of Krohn–Rhodes' theorem, have always assumed a right-to-left bracketing of the operands. We consider here the left-to-right bracketing, which is generally weaker. More precisely, we are interested in characterizing for any pseudovarieties of monoids U, V the smallest pseudovariety W that contains U and such that W □ V = W. This allows us to obtain new decomposition results for a number of important varieties such as DA, DO and DA * G. We apply these results to characterize the regular languages definable with generalized first-order sentences using only two variables and to shed new light on recent results on regular languages recognized by bounded-depth circuits with a linear number of wires and regular languages with small communication complexity.