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May 20 at 16:03 comment added Mařík Savenko @BernardoSubercaseaux That's a good insight. What if I will consider all $u,v$ such that the path $P:u---> v$ with the smallest weight-edge has $2$ edges in it. I will look to find only these $u,v$. I think it'll relax the problem a bit.
May 20 at 16:01 comment added Mařík Savenko @MajidZohrehbandian Wouldn't that simply be $|V||E|$?
May 19 at 18:40 comment added Majid Zohrehbandian If you are not attempting to enumerate all triangles in the second problem, then you can introduce a new graph $H=G_1$x$G_2$x$G_3$x$G_4$, where $G_k=(V,E_k=\{\})$ is a null graph, for each edge $e_{ij}\in E$ introduce a directed edge between vertex $i\in G_k$ and vertex $j\in G_{k+1}$. Note that, you can introduce $V_1=V_4=\{v\}$ and $V_2=V_3=N_v$. Now, in H, shortest path between each vertex v in $G_1$ and the same vertex v in $G_4$ is similar to a minimum triangle on vertex v in G.
May 16 at 16:28 comment added Bernardo Subercaseaux Note that if you take any positively weighted graph $G$, add a new special vertex $x$, and then add edges $e_u := \{u, x\}$ for every $u \in V(G)$, with weight $w(e_u) = +\infty$ each (e.g., $+\infty := \max_{e \in E(G)} w(e)$), then all pairs of nodes have length $2$ paths, so your problem becomes general APSP. The modified graph has only one extra vertex and a linear number of extra edges, so a $|V|^2$ algorithm for your problem would imply a $|V|^2$ algorithm for APSP.
S May 15 at 15:34 history bounty started Mařík Savenko
S May 15 at 15:34 history notice added Mařík Savenko Canonical answer required
May 12 at 12:20 history edited Mařík Savenko CC BY-SA 4.0
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May 10 at 12:46 history edited Mařík Savenko CC BY-SA 4.0
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May 9 at 20:27 history asked Mařík Savenko CC BY-SA 4.0