HElib 2.3.0, July 2023

(tagged as v2.3.0)

Added support for processing queries with the NOT operator homomorphically.
Introduced the NOT Expr, and a corresponding inline NOT QueryExpr Within the weights, or CNF, framework:
- Extensions to the ExpandOr() function to queries with NOT operators, via a new function negate()
- New function Tidy() which eliminates duplicate columns in inner clauses, or columns and their negation in inner clauses that can be created by squashing ORs. It also eliminates empty clauses,
- Put the code from build() which constructed the corresponding weights into a new function buildWeights(), and extended this to the case there are negations of columns
- New framework which evaluates queries homomorphically directly from the string:
- New function removeOr() within the QueryBuilder class which generates a new query string which is logically equivalent, but only has Ands and Nots
- Overloaded contains() function that takes a string instead of a QueryType, and evaluates the RPN directly using a stack of ciphertexts
Updated CI
- Deprecated build&test on Ubuntu 20.04
- Updated build&test on Ubuntu 22.04
- Added build&test on macOS 12 and MacOS13
Bug Fixes

Co-authored-by: @TabOg
Co-authored-by: @faberga
Co-authored-by: @jlhcrawford
Co-authored-by: @hamishun

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