Notation PreferencesSecure and Distributed Computing

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KeyMeaningYour SymbolDefault
gaussReal Gaussian distributionN\mathcal{N}
cgaussCircularly symmetric complex GaussianCN\mathcal{CN}
covmatCovariance matrixΣ\boldsymbol{\Sigma}
snrSignal-to-noise ratioSNR\text{SNR}
n0One-sided noise power spectral densityN0N_0
bwSignal bandwidth (Hz)WW
noisevarNoise variance / noise powerσ2\sigma^2

Universal Conventions

Fixed conventions used throughout the SC book. These are standard across the secure-and-distributed-computing literature and are not customizable.

General Mathematics

SymbolMeaning
R,C\mathbb{R}, \mathbb{C}Real and complex number fields
Fq\mathbb{F}_qFinite field of order qq (prime power)
Zp\mathbb{Z}_pIntegers modulo pp
Rn,Cn,Fqn\mathbb{R}^n, \mathbb{C}^n, \mathbb{F}_q^nnn-dimensional vector spaces over the indicated field
S|\mathcal{S}|Cardinality of set S\mathcal{S}
O(),Θ()\mathcal{O}(\cdot), \Theta(\cdot)Big-O and tight-bound asymptotic notation
\triangleqDefined as

Distributed Computing System

SymbolMeaning
NNNumber of workers (Parts I–II) or databases (Part IV)
nnNumber of users in federated learning (Parts III, V)
KKRecovery threshold (Part II); number of files (Part IV)
TTCollusion threshold (PIR) or Byzantine fault tolerance
BBMaximum number of Byzantine workers
μ[0,1]\mu \in [0, 1]Computation load: fraction of dataset stored per worker
Δ\DeltaCommunication load (bits exchanged, normalized)
gk\mathbf{g}_kLocal gradient (or message) of user/worker kk
G\mathbf{G}Aggregated gradient: k=1ngk\sum_{k=1}^n \mathbf{g}_k

Cryptographic / Coding Primitives

SymbolMeaning
ssSecret to be shared among parties
sks_kSecret share held by party kk
p(x)p(x)Encoding polynomial (Shamir / coded computing)
(t,n)(t, n)-thresholdAny tt shares reconstruct; any t1t-1 learn nothing
CPIRC_{\text{PIR}}Private-information-retrieval capacity
Rcomp,RcommR_{\text{comp}}, R_{\text{comm}}Computation and communication rates

Wireless / Channel

SymbolMeaning
H\mathbf{H}Channel matrix (where applicable, Part V)
w\mathbf{w}Additive white Gaussian noise vector
SNR\text{SNR}Signal-to-noise ratio