(No) Hard Feelings!

No hard triggers under speculation ? (

There Are No Sparse NPW-Hard Sets

In this paper we prove that, in the context of weak machines over IR, there are no sparse NP-hard sets.

The Coma Cluster hard X - ray spectrum revisited : still no evidence for a hard tail

In this note, we reply to Fusco-Femiano et al. 2004 (FF04) and Fusco-Femiano et al. 2006 (FF06), who cast doubts on our analysis of the PDS observations of the Coma Cluster which we describe in Rossetti & Molendi 2004 (RM04). We discuss the main issues in FF06 and we confirm that the available data do not allow to firmly establish the presence of a non-thermal component in the hard X-ray spectr...

Buying random votes is as hard as buying no-votes

In voting systems where a mark in a fixed position may mean a vote for Alice on a ballot, and a vote for Bob on another ballot, an attacker may coerce voters to put their mark at a certain position, enforcing effectively a random vote. This attack is meaningful if the voting system allows to take receipts with them and/or posts them to a bulletin board. The coercer may also ask for a blank rece...

There are no zero-hard problems in multiparty communication complexity

We study the feasibility of generalizing the notions of completeness and hardness in 2-party communication complexity (Babai, Frankl, Simon, FOCS 1986) to the “number-on-forehead” (NOF) model of k-party communication complexity with k ≥ 3 (Chandra, Furst, Lipton, STOC 1983). Beame et al. (Theory of Computing, 2010) suggest that the kparty version of NP may not have any complete families under t...