An ontological characterization of time-series and state-sequences for data mining

Time-series and sequences are important patterns in data mining. Based on an ontology of time-elements, this paper presents a formal characterization of time-series and state-sequences, where a state denotes a collection of data whose validation is dependent on time. While a time-series is formalized as a vector of time-elements temporally ordered one after another, a state-sequence is denoted as a list of states correspondingly ordered by a time-series. In general, a time-series and a state-sequence can be incomplete in various ways. This leads to the distinction between complete and incomplete time-series, and between complete and incomplete state-sequences, which allows the expression of both absolute and relative temporal knowledge in data mining.

The palaeoenvironment and stratigraphy of Late Cretaceous Chalks

Since the publication of Hancock's ‘the Petrology of the Chalk’ there have been numerous developments in our appreciation of the palaeoenvironment and stratigraphie correlation of the UK Chalk. This work presents a review of some of the key developments over the last 30 years. Our detailed understanding of Chalk lithostratigraphy and advances in our understanding of chalk sedimentation indicate that large-scale mass transport and re-sedimentation of chalks by low-angle suspension flows is required to explain the observed thickness variations. The provenance of clay minerals and the process of flint and granular phosphate formation are discussed. The growing importance of isotopic studies in high resolution stratigraphy and improving our understanding of the late Cretaceous oceans and climate are emphasized. Developments in lithostratigraphic studies and recent proposals for a new stratigraphie division of the Chalk in the UK are evaluated.