A study of the boundedness in probability of the set of possible wealth outcomes of an economic agent facing constraints, and with limited access to information , is undertaken. The wealth-process set is abstractly structured with reasonable economic properties, instead of the usual practice of taking it to consist of stochastic integrals against a semimartingale integrator. We obtain the equivalence of (a) the boundedness in probability of  wealth outcomes with (b) the existence of at least one deflator that make the deflated wealth processes have a generalized supermartingale property. Specializing in the case of full  information, we obtain as a consequence that in a viable market all wealth processes have versions that are semimartingales .
We undertake a study of market viability from the perspective of a financial agent with limited access to information . The set of wealth processes available to the agent is structured with reasonable economic properties, instead of the usual practice of taking it to consist of stochastic integrals against a semimartingale integrator. We obtain the equivalence of the boundedness in probability of the set of terminal wealth outcomes with the existence of at least one strictly positive deflator that makes the deflated wealth processes have a generalized supermartingale property. Specializing to the case of full agent's information, we obtain as a consequence that in a viable market every properly discounted wealth processes has a version that is a semimartingale .
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A study of the boundedness in probability of the set of possible wealth outcomes of an economic agent facing constraints, and
We undertake a study of market viability from the perspective of a financial agent
R
, is undertaken. The wealth-process set is abstractly
. The set of wealth processes available to the agent is
D
(a)
A
the set of terminal
D
(b)
R
deflator that make
strictly positive deflator that makes
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in
to
A
agent's
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all wealth processes have versions that are semimartingales
every properly discounted wealth processes has a version that is a semimartingale