Could anyone please explain me clearly why we have to do

low[vertex]=min(low[vertex],dis[i]);

Yeah!I know that is for lowest discovery time determination.But my question is that all the time we put minimum time in the current node comparing with its adjacent nodes,but not increase the time.My question is two or more nodes cant visit at a time.But lowest time show that,it can do that.But how? Could anyone please clear me out?Actually,i read more than 5/6 resources,but i couldn't get that.There all says about subtree,ancestor,blah blah,but my memory couldn't make a sense for that,what they actually want to say.

Thanks in advance.

Following is the psuedocode of finding out articulation point.

time = 0
function DFS(adj[][], disc[], low[], visited[], parent[], AP[], vertex, V)
        visited[vertex] = true
        disc[vertex] = low[vertex] = time+1
        child = 0
        for i = 0 to V
                if adj[vertex][i] == true
                        if visited[i] == false
                                child = child + 1
                                parent[i] = vertex
                                DFS(adj, disc, low, visited, parent, AP, i, n, time+1)
                                low[vertex] = minimum(low[vertex], low[i])
                                if parent[vertex] == nil and child > 1
                                        AP[vertex] = true
                                if parent[vertex] != nil and low[i] >= disc[vertex]
                                        AP[vertex] = true
                        else if parent[vertex] != i
                                low[vertex] = minimum(low[vertex], disc[i])