Client, server, and client-server system adapted for updating a client-item matrix

A client (i) adapted for updating individual elements (rij) of a client-item matrix (R) by means of Collaborative Filtering, R = XTY. The matrix (R) comprises a plurality of individual elements (rij),each individual element relating to a specific client (i) and a specific item (j). The client (i) utilizes an individual part (Ai) of a first model component (A) and at least one element of local client data (ui). The first model component (A) is a factor matrix A = X(i, k) comprising a plurality of client factor vectors (xi). The individual part (Ai) of the first model component (A) is the client factor vector (xi) for said client (i). The client (i) is connected to a server utilizing a second model component (B) and a global set of items (j1,..., jM). The second model component (B) is a factor matrix B = Y(J, k) comprising a plurality of item factor vectors (yj). The client (i) is configured to assign the individual part (Ai) of the first model component (A) to the client (i) and download a second model compone