We study the strict type assignment for λμ that is presented in [7]. We define a notion of approximants of λμ-terms, show that it generates a semantics, and that for each typeable term there is an approximant that has the same type. We show that this leads to a characterisation via assignable types for all terms that have a head normal form, and to one for all terms that have a normal form, as ...

We consider exact learning or identification of monotone Boolean functions by only using membership queries. It is shown that almost all monotone Boolean functions are polynomially identifiable in the input number of variables as well as the output being the sum of the sizes of the CNF and DNF representations.  2001 Elsevier Science B.V. All rights reserved.

Reflection tomography in the migrated domain can help reconstruct heterogeneous, anisotropic velocity fields needed for accurate depth imaging of complex geologic structures. The presence of anisotropy, however, increases the uncertainty in velocity analysis and typically requires a priori constraints on the model parameters. Here, we develop a 2D P-wave tomographic algorithm for heterogeneous ...

The differential semblance method employs an objective function, which measures the error in moveout between neighboring traces. Differential semblance velocity estimators have well-defined and smooth high frequency asymptotics compared to the conventional velocity analysis. Numerical experiments with CMP gathers and layered models illustrate theoretical properties of DS objectives. (reference ...

SUMMARY In this paper, we approach automated seismic interference (SI) identification for towed-streamer acquisitions in a new way. We show how to teach a neural network to identify SI based on features the human brain would use for such a task. This includes describing geophysical attributes such as amplitudes and wavefield propagation directions with instantaneous and multishot statistical me...

The ability to produce from low permeability, tight gas reservoirs is directly tied to the ability to repetitively perform successful hydraulic fracturing in a series of closely spaced wells. The key question is whether the induced fractures remain open and permeable, which is in part a function of the stress field and the emplacement of proppant. We study the ability to detect and characterize...

A prefix normal word is a binary word with the property that no substring has more 1s than the prefix of the same length. This class of words is important in the context of binary jumbled pattern matching. In this paper we present results about the number pnw(n) of prefix normal words of length n, showing that pnw(n) = Ω ( 2n−c √ n lnn ) for some c and pnw(n) = O ( 2(lnn) n ) . We introduce eff...

Abstract In a soliton sector of quantum field theory, it is often convenient to expand the fields in terms normal modes. Normal mode creation and annihilation operators can be ordered, their ordered products have vanishing expectation values one-loop ground state. The Hamiltonian however, usually basis which create plane waves. this paper we find Wick map between two orderings. For concreteness...