Short-term memory allows individuals to recall stimuli, such as numbers or words, for several seconds to several minutes without rehearsal. Although the capacity of short-term memory is considered to be 7 ±?2 ...Short-term memory allows individuals to recall stimuli, such as numbers or words, for several seconds to several minutes without rehearsal. Although the capacity of short-term memory is considered to be 7 ±?2 items, this can be increased through a process called chunking. For example, in Japan, 11-digit cellular phone numbers and 10-digit toll free numbers are chunked into three groups of three or four digits: 090-XXXX-XXXX and 0120-XXX-XXX, respectively. We use probability theory to predict that the most effective chunking involves groups of three or four items, such as in phone numbers. However, a 16-digit credit card number exceeds the capacity of short-term memory, even when chunked into groups of four digits, such as XXXX-XXXX-XXXX-XXXX. Based on these data, 16-digit credit card numbers should be sufficient for security purposes.展开更多
Under the assumption of sixth power large.sieve mean-value of Dirichlet L-function, we improve Bombieri＇s theorem in short intervals by virtue of the large sieve method and Heath-Brown＇s identity.
Motivated by a discrete-time process intended to measure the speed of the spread of contagion in a graph,the burning number b(G)of a graph G,is defined as the smallest integer k for which there are vertices x1,…xk su...Motivated by a discrete-time process intended to measure the speed of the spread of contagion in a graph,the burning number b(G)of a graph G,is defined as the smallest integer k for which there are vertices x1,…xk such that for every vertex u of G,there exists i∈{1,…k}with dG(u,xi)≤k−i,and dG(xi,xj)≥j−i for any 1≤i<j≤k.The graph burning problem has been shown to be NP-complete even for some acyclic graphs with maximum degree three.In this paper,we determine the burning numbers of all short barbells and long barbells,respectively.展开更多
文摘Short-term memory allows individuals to recall stimuli, such as numbers or words, for several seconds to several minutes without rehearsal. Although the capacity of short-term memory is considered to be 7 ±?2 items, this can be increased through a process called chunking. For example, in Japan, 11-digit cellular phone numbers and 10-digit toll free numbers are chunked into three groups of three or four digits: 090-XXXX-XXXX and 0120-XXX-XXX, respectively. We use probability theory to predict that the most effective chunking involves groups of three or four items, such as in phone numbers. However, a 16-digit credit card number exceeds the capacity of short-term memory, even when chunked into groups of four digits, such as XXXX-XXXX-XXXX-XXXX. Based on these data, 16-digit credit card numbers should be sufficient for security purposes.
基金Tianyuan Mathematics Foundation (11026075)the NSF (10971119) of Chinathe NSF (ZR2009AQ007) of Shandong Province
文摘Under the assumption of sixth power large.sieve mean-value of Dirichlet L-function, we improve Bombieri＇s theorem in short intervals by virtue of the large sieve method and Heath-Brown＇s identity.
基金supported by the National Natural Science Foundation of China(Nos.11971158,12371345,11971196).
文摘Motivated by a discrete-time process intended to measure the speed of the spread of contagion in a graph,the burning number b(G)of a graph G,is defined as the smallest integer k for which there are vertices x1,…xk such that for every vertex u of G,there exists i∈{1,…k}with dG(u,xi)≤k−i,and dG(xi,xj)≥j−i for any 1≤i<j≤k.The graph burning problem has been shown to be NP-complete even for some acyclic graphs with maximum degree three.In this paper,we determine the burning numbers of all short barbells and long barbells,respectively.
