Table 1 Meanings of the symbols used in this article.

From: Bipolar fuzzy outerplanar graphs approach in image shrinking

Notations

Meanings

\(G\)

Crisp graph

\(\psi\)

an arbitrary graph

\({\mathbb{V}}\)

vertices in the set of \(\psi\)

\({\mathbb{E}}\)

edges in the set of \(\psi\)

\({\mathbb{X}}\)

universal set

\({\mathbb{A}}\)

a fuzzy set

\({\mathring{\rm A}}\)

Bipolar fuzzy set

\(\mathcal{B}\)

Bipolar fuzzy graph

\({\mu }_{\mathcal{B}}^{\mathcal{P}}(\mathcalligra{x})\)

Positive membership degree

\({\mu }_{\mathcal{B}}^{\mathcal{N}}(\mathcalligra{x})\)

Negative membership degree

\({O}^{+}\left(\psi \right)\)

Positive order

\({O}^{-}\left(\psi \right)\)

Negative order

\({S}^{+}\left(\psi \right)\)

Positive size

\({S}^{-}\left(\psi \right)\)

Negative size

\(\mathfrak{a}\mathfrak{b}\)

Bipolar fuzzy edge

\({I}_{\mathfrak{a}\mathfrak{b}}\)

Strength of the bipolar fuzzy edge (\(\mathfrak{a},\mathfrak{b})\)

\(\tau\)

The function defining the degree of membership for each vertex

\(\delta\)

The function defining the degree of membership for each edge

\(\wedge\)

Minimum

\(\vee\)

Maximum