[Job-offers-cs] Postdoctoral position at INRIA Lille, France, INOCS TEAM, Services Pricing for cloud computing

[Pekka Orponen]

-------- Forwarded Message --------
Subject: [DMANET] Postdoctoral  position at INRIA Lille, France, INOCS 
TEAM, Services Pricing for cloud computing
Date: Fri, 17 Apr 2020 11:25:31 +0200
From: Luce Brotcorne <luce.brotcorne at inria.fr>
To: DMANET at zpr.uni-koeln.de


Services Pricing for cloud computing
Contact: Bernard Fortz bfortz at ulb.ac.be Luce Brotcorne : 
Luce.Brotcorne at inria.fr
Inria Lille Nord Europe, INOCS Team
To apply send a CV and a cover letter to B Fortz and L. Brotcorne before 
April 26.


Context

Cloud computing is offering a variety of services to end users like the 
management and storage of data, the processing of jobs or the access to 
platforms on demand.

The service level agreement (SLA) is the contract between the service 
provider and the customers. It defines the services that the provider 
will furnish. The quality of service (QoS) represents the capacity of 
the service provider to respect the SLA subscribed by the clients. 
Focusing on the “Platform as a service” or the Infrastructure as a 
service” context, the QoS can be deteriorated if the delay of processing 
increases. This occurs when the amount of resources required by the 
users are not sufficient to satisfy the demand.

To solve this problem the cloud provider can either reduce the maximum 
resources consumption of users in the SLA or invest in additional 
servers or define incentives like the price to smooth out the demand 
over time. This last solution is under study in this project.

When defining the service prices, the cloud service provider objectives 
are to increase the benefits while insuring a good quality of service. 
Three pricing strategies can be identified in the literature : i) 
value-based pricing, based on the demand of users, ii) cost-based 
pricing, based on the costs for the service provider, iii) market-based 
pricing considering both aspect, like auction model for example.
Unfortunately, these “pay-per-use fixed pricing” charging users for what 
they consume can't be used to limit the peak periods of usage by the 
users. In order to reach this objective, prices need to vary over time 
and according to the amount of resources required.

To intrinsically integrate the decisions of the cloud users maximizing 
their utility into the decision making process of the cloud service 
provider the cloud service pricing problem (CSPP) can be modeled as a 
bilevel optimization problem.

Bilevel Programming is a fairly recent branch of optimization that deals 
with programs whose constraints embed an auxiliary optimization problem 
. More precisely bilevel problems involve two decision makers (a leader 
and a follower) interacting sequentially and hierarchically. In our 
context the leader is the cloud operator defining a pricing strategy 
taking explicitedly into account the reactions of the users. For the 
CSPP the objective of the leader is to maximize the revenue (profit 
-costs) and decrease the peaks while the objective of the users is to 
minimize their cost and they delay.

Bilevel programming problems, being generically difficult to solve due 
to their non-convexity and non differentiability, the structure of the 
problem will be exploited to define efficient solution methods. For 
example when the optimization problem is convex for fixed leader 
decisions, it can be replaced by its KKT conditions leading to a single 
level optimization problem.



- - Research objective--

The goal of the post-doc is to study the properties of bilevel bilinear 
programs for the SCPP and develop efficient solution methods. Numerical 
results should be studied and discussed. This field of research is and 
very innovative and promising in an industrial context.


Where

I NRIA Lille Nord Europe, INOCS Team

The INOCS team aims to develop new models, algorithmic techniques and 
implementations for optimization problems with complex structure (CS). 
More precisely, we consider that an optimization problem presents a CS 
when for example it involves some hierarchical leader-follower structure 
(bilevel optimization). Luce Brotcorne is specialist in bilevel 
optimization with a particular expertise to solve pricing problems, 
while Bernard Fortz has also a strong experience in decomposition 
methods that will be at the core of algorithms developed in the project

A post doctoral position is available in the Inocs team for the topic 
``Services Pricing for cloud computing’’.


Knowledge

Candidates should hold a PhD Thesis in Operations research, mathematics, 
computer science, or similar fields and should ideally have a solid 
background in discrete optimization, integer programming, decomposition 
techniques. Computer science skills in algorithmic and C/C++ development 
are also welcome.
Knowledge of French is not required, but good communication skills and a 
solid knowledge of English are essential.