Dear @Nadim, the following paper entitled:" Hypothetical Reasoning From Situation Calculus to Event Calculus" by A Provetti discusses this issue. Abstract: Pinto and Reiter have argued that the Situation Calculus improved with time handling axioms subsumes the features of linear time temporal formalisms such as Event Calculus and Interval Logic In this note we nd answers to some of their remarks by showing a modied version of Event Calculus that seems to match Situation Calculus handling of hypothetical reasoning and projection Further consideration on semantics and expressive power of Event Calculus put forward by Pinto and Reiter are discussed in the light of recent proposal for an unifying semantics for languages for time and actions.

See the paper at the link:

www2.cs.uregina.ca/~temporal/time94/provetti.pdf

In addition to the incisive observations by @Abedallah M Rababah, the relationship between a discrete event calculus and the situation calculus is investigated in

E.T. Mueller, Discrete event calculus with branching time, 2007:

http://alumni.media.mit.edu/~mueller/papers/ecsc.pdf

See Section 5, starting on page 6, where the equivalence of a branching discrete event calculus (BDEC) and the situation calculus is covered.   Perhaps you will find Section 7 (Actual situations and events), starting page 17, interesting.    In that section,  the BDEC is extended and used to distinguish between hypothetical and actual situations.    Also, Section 8 (Related work), starting on page 18, is very detailed.

Dear Nadim

This article is very useful "A comparison of Situation Calculus and Event Calculus"

n this report, we make a comparison of the two formalisms; first outlining the basic ontologies and axioms that are used in the language. A comparison of features and Possible extensions to each language to make it more compat- ible with multi-agent systems are then presented. Differences in dealing with underlying logical problems, temporal representations, non-determinism and concurrency are all examined. Finally, we will explore solutions which have been put

https://www.researchgate.net/publication/250025402_A_comparison_of_Situation_Calculus_and_Event_Calculus

Article A comparison of Situation Calculus and Event Calculus

Thank so much. I am sure that it will be very useful.

Best wishes,

Nadim

"On the relation between situation calculus and event calculus"

http://www.sciencedirect.com/science/article/pii/S0743106696001239

Thank you so much. This is very helpful.

Nadim

The article referred by Nisar K S is the best reference of what you're looking for.