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I like to use the abbreviations "w/" for "with" and "w/o" for "without" on my powerpoint slides and also in emails. According to this discussion Are "w/o", "w/", "b/c" common abbreviations in the US? the meaning of these abbreviations is well known in English speaking countries.
Recently, a colleague pointed out that these abbreviations do not look very professional on slides presented at some conferences. Since we are both non-native speaker, I'd like to know your opinion on using them on slides, does that look awkward or non-professional to native-speakers?
(I am working in natural sciences, if this matters)