A useless state in a pushdown automaton is never entered on any input string. Con- sider the problem of determining whether a pushdown automaton has any useless states. Formulate this problem as a language and show that it is decidable

Write a computer program to calculate the three-phase fault current for a fault at f in figure 1.16, with the network normal, and with one line at a time removedproblems 1.1 write a computer program to calculate the three-phase fault current for a fault at f in figure 1.16, with the network normal, and with one line at a time removed 20 power system relaying from service. the positive-sequence impedance data are given in the accompanying table. use the commonly made assumption that all prefault resistance values are (1.0+j0.0) pu, and neglect all resistance values. calculate the contribution to the fault flowing through the cb b and the voltage at that bus. for each calculated case, consider the two possibilities: cb b2 closed or open. the latter is known as the stub-end fault í• figure 1.16 problem 1.1 system data for figure 1.16 from to positive sequence 0.0+j0.1 0.05j0.15 0.04 j0.2 0.01 jo.i 0.015 + j0.15 0.01 j0.19 0.01 +j0.19 0.03+j0.1 0.0+j0.08 6 6 6 from service. the positive-sequence impedance data are given in the accompanying table. use the commonly made assumption that all prefault resistance values are (1.0 + j 0.0) pu, and neglect all resistance values. calculate the contribution to the fault flowing through the cb b1, and the voltage at that bus. for each calculated case, consider the two possibilities: cb b2 closed or open. the latter is known as the “stub-end” fault.

Select the correct answer. andre was recently hired by an organization to check for system vulnerabilities. he is supposed to exploit these vulnerabilities and create a report on the extent of damage to which the system was susceptible. what position does andre hold in this organization? a. information security analyst b. information assurance manager c. penetration tester d. network security engineer e. chief information security officer

Visualizing a game of “tag” to remember the meaning of contagious