title: Topological entropy of DNA sequences.
abstract: BACKGROUND
  Topological entropy has been one of the most difficult to implement of all the entropy-theoretic notions. This is primarily due to finite sample effects and high-dimensionality problems. In particular, topological entropy has been implemented in previous literature to conclude that entropy of exons is higher than of introns, thus implying that exons are more 'random' than introns.
  
  
  RESULTS
  We define a new approximation to topological entropy free from the aforementioned difficulties. We compute its expected value and apply this definition to the intron and exon regions of the human genome to observe that as expected, the entropy of introns are significantly higher than that of exons. We also find that introns are less random than expected: their entropy is lower than the computed expected value. We also observe the perplexing phenomena that introns on chromosome Y have atypically low and bimodal entropy, possibly corresponding to random sequences (high entropy) and sequences that posses hidden structure or function (low entropy).
  
  
  BACKGROUND
  A Mathematica implementation is available at http://www.math.psu.edu/koslicki/entropy.nb
  
  
  BACKGROUND
  koslicki@math.psu.edu
  
  
  BACKGROUND
  Supplementary data are available at Bioinformatics online.
authors.affiliation: Department of Mathematics, Pennsylvania State University, State College, PA 16801, USA. koslicki@math.psu.edu
authors.forename: David
authors.initials: D
authors.lastname: Koslicki
mesh_terms: D041322:Chromosomes, Human, Y; D004247:DNA / Q000737:chemistry*; D019277:Entropy; D005091:Exons; D015894:Genome, Human; D006801:Humans; D007438:Introns; D017422:Sequence Analysis, DNA
chemical_list: D004247:DNA