One says that history H is recoverable if, whenever transact

One says that history H is recoverable if, whenever transaction Ti reads (some item x) from transaction Tj (i 6= j) in H and Ci occurs in H, then Cj ≺S Ci . Ti “reads x from” Tj in H if 1. Wj(x) ≺H Ri(x), and 2. Ajnot ≺H Ri(x), and 3. if there is some Wk(x) such that Wj(x) ≺H Wk(x) ≺H Ri(x), then Ak ≺H Ri(x). Which of the following histories are recoverable?H1 ={W2(x),W1(x),R3(x),R1(x),C1,W2(y),R3(y),R3(z),C3,R2(x),C2}H2 ={R3(z),R3(y),W2(y),R2(z),W1(x),R3(x),W2(x),R1(x),C1,C2,C3}H3 ={R3(z),W2(x),W2(y),R1(x),R3(x),R2(z),R3(y),C3,W1(x),C2,C1}H4 ={R2(z),W2(x),W2(y),C2,W1(x),R1(x),A1,R3(x),R3(z),R3(y),C3}

You can hire someone to answer this question! Yes, essay96.com has paper writers dedicated to completing research and summaries, critical thinking tasks, essays, coursework, and other homework tasks. It's fast and safe.