Kouichi Hirata

Learn More
We introduce a tree distance function based on multi-sets. We show that this function is a metric on tree spaces, and we design an algorithm to compute the distance between trees of size at most n in O(n) time and O(n) space. Contrary to other tree distance functions that require expensive memory allocations to maintain dynamic programming tables of(More)
70-kDa heat shock protein family is a molecular chaperone that binds to a variety of client proteins and peptides in the cytoplasm. Several studies have revealed binding motifs between 70-kDa heat shock protein family and cytoplasmic proteins by conventional techniques such as phage display library screening. However, little is known about the binding motif(More)
In this paper, we introduce ordered clauses as defined a sequence of literals, and investigate the properties of generalizations for ordered clauses. Furthermore, we show that the subsumption problem for ordered clauses is NP-complete, as similar as the subsumption problem for ordinal clauses. Hence, the definition that a clause is a set of literals is(More)
To date an increasing number of T-cell epitopes derived from various tumor-associated antigens have been reported, and they proved to play significant roles for tumor rejection both in vivo and in vitro. Survivin was originally identified as a member of the inhibitor of apoptosis protein family. Expression of this gene is developmentally regulated. Although(More)
Structural, cellular and nuclear abnormalities of hepatocytes are a histological hallmark of well-differentiated, small hepatocellular carcinoma (HCC) or its borderline lesion. This study revealed that several hepatocellular abnormalities found in these hepatocellular neoplasms were also found in non-cirrhotic stages of primary biliary cirrhosis (PBC) in(More)
The second-order matching problem is the problem of determining, for a finite set {〈ti, si〉 | i ∈ I} of pairs of a second-order term ti and a first-order closed term si, called a matching expression, whether or not there exists a substitution σ such that tiσ = si for each i ∈ I . It is well-known that the second-order matching problem is NP-complete. In(More)
In this paper, we introduce a diamond episode of the form s1 → E → s2, where s1 and s2 are events and E is a set of events. The diamond episode s1 → E → s2 means that every event of E follows an event s1 and is followed by an event s2. Then, by formulating the support of diamond episodes, in this paper, we design the algorithm FreqDmd to extract all of the(More)
In this paper, we study the problem of mining frequent diamond episodes efficiently from an input event sequence with sliding a window. Here, a diamond episode is of the form a → E → b, which means that every event of E follows an event a and is followed by an event b. Then, we design a polynomial-delay and polynomial-space algorithm PolyFreqDmd that finds(More)