RESEARCH ARTICLE


Braess's Paradox and Power-Law Nonlinearities in Five-Arc and Six-Arc Two-Terminal Networks



Claude M. Penchina*
Department of Physics, Hasbrouck Laboratory, University of Massachusetts at Amherst, Amherst Massachusetts, 01003, USA.

Additional Affiliations: Department of Physics, King's College, Strand, London WC2R-2LS, UK, and Gilora Associates, Flemington, New Jersey, NJ 08822, USA




Article Metrics

CrossRef Citations:
1
Total Statistics:

Full-Text HTML Views: 161
Abstract HTML Views: 317
PDF Downloads: 204
Total Views/Downloads: 682
Unique Statistics:

Full-Text HTML Views: 118
Abstract HTML Views: 212
PDF Downloads: 178
Total Views/Downloads: 508



Creative Commons License
© 2009 Claude M. Penchina;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Physics, Hasbrouck Laboratory, University of Massachusetts at Amherst, Amherst Massachusetts,01003, USA; E-mail: penchina@physics.umass.edu


Abstract

We extend a general network theorem of Calvert and Keady (CK) relating to the minimum number of arcs needed to guarantee the occurrence of the Braess Paradox. We rephrase the CK theorems and express our proof in the terminology of traffic networks.

CK described their theorem in relation to a two-terminal network of liquid in pipes. “Approximately stated, it is: if every relationship between flow and head difference is not a power law, with the same (power) s on each arc, given at least 6 pipes, one can arrange (lengths of) them so that Braess's paradox occurs, i.e. one can increase the conductivity of an individual pipe yet require more power to maintain the same consumptions.” In relation to the original Braess situation of traffic network flows, the relationship is between flow and link-cost on a congested link.

Our extended theorem shows that 5 pipes (roads, links, arcs) arranged in a Wheatstone Bridge (WB) network (as in the original Braess network) are necessary and sufficient to produce a Braess paradox (BP) in a two-terminal network (not limited to liquid in pipes) if at least one of the five has a different conductivity law (not power s).

Keywords: Braess's paradox, network theorems, power law non-linearities, wheatstone bridge.