## Abstract

In this paper the problem is posed of the prescription of the so-called Boltzmann-Grad (BG) limit (

to the classical statistical mechanics of finite hard-sphere systems recently developed (Tessarotto et al., 2013-2017). The issue addressed here concerns the prescription of the BG-limit operator and specifically the non-commutative property of

*L*) for the N−body system of smooth hard-spheres which undergo unary, binary as well as multiple elastic instantaneous collisions. The statistical description is couched in terms of the Master kinetic equation, i.e., the kinetic equation which realizes the axiomatic ”ab initio” approach_{BG}to the classical statistical mechanics of finite hard-sphere systems recently developed (Tessarotto et al., 2013-2017). The issue addressed here concerns the prescription of the BG-limit operator and specifically the non-commutative property of

*L*with the free-streaming operator which enters the same kinetic equation. It is shown that the form of the resulting limit equation remains in principle non-unique, its precise realization depending critically on the way the action of the same operator is prescribed. Implications for the global prescription of the Boltzmann equation are pointed out._{BG}Original language | English |
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State | Published - 15 May 2017 |

### Publication series

Name | arXiv preprint |
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## Keywords

- math-ph
- math.MP