1. Towards a Theory of Semantic Communication Jie Bao, RPI Joint work with Prithwish Basu, Mike Dean, Craig Partridge, Ananthram Swami, Will Leland and Jim Hendler
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6. Misunderstanding can be costly Mars Climate Orbiter (1998-1999), $125 million Expressed Pound (lb F ) Interpreted Newton (N) Image Source: Wikipedia, http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Communications_loss
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10. Shannon, 1948 message message Shannon Model Signal Signal Expressed Message (e.g., commands and reports) Expressed Message From IT to SIT (Classical) Information Theory Semantic Information Theory Semantic Channel
11. A Three-level Model (Weaver) Transmitter Receiver Destination Source Physical Channel Technical message Technical Noise Intended message Expressed message Semantic Transmitter Semantic Receiver Semantic Noise Shared knowledge Local knowledge Local knowledge (effectiveness factors) C: Effectiveness B: Semantic A: Technical
12. A Semantic Communication Model Message generator World model Background Knowledge Inference Procedure Messages Sender Message interpreter World model Background Knowledge Inference Procedure Receiver W s W r K s K r I s I r {m} World M: Message Syntax Feedback (?) observations Ms Mr
18. Which sentence is more “surprising”? ``Rex is not a tyrannosaurus'' ``Rex is not a dog''
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20. “ Semantics” of DNA Image courtesy: http://www.yourdictionary.com/dna http://www.pnl.gov/biology/images/protein_molecule.jpg “ Syntax” Model (“Semantics”) Gene expression
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34. Semantic Noise and Channel Coding “ coffee machine” “ copy machine” “ Xerox ” “ Xerox” “ copy machine” p->ff ? ? 0.9 0.1 1.0 W X Y W’ Scenario developed based on reports in http://english.visitkorea.or.kr/enu/AK/AK_EN_1_6_8_5.jsp and http://blog.cleveland.com/metro/2011/03/identifying_photocopy_machine.html
For another example of information source in a broader sense, information carried by DNA are encoded using a four-letter alphabet (bases A, G, C, U). DNA's syntactical entropy can be obtained using statistical studies of bases or sequences of bases, with estimation ranging from 1.6 to 1.9 bits per base~\\cite{LY96,citeulike:769969,schmidt1997}. However, the ``semantics'' of DNA is only expressed after a complex process, producing functional gene products such as RNAs or proteins. The process is not yet fully understood, but it has been observed that variations of DNA do not necessarily result in different gene products [Citation of degenracy of DNA code], nor DNA will be expressed in the exactly same way under different conditions [citation of genetic expression variation]. If we measure the amount of information carried in a DNA based on its functional gene products, our conjecture is that it might be different from the DNA's syntactical entropy.
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