Logic in html

Firstly a few html symbols taken from W2C Entities
≠ Not equal to
≡ Not identical to
≤ Less than or equal to
⊂ Subset of
⊃ Superset of
⊄ not a subset of
⊆ subset of or equal to
⊇ superset of or equal to
⊕ circled plus = direct sum
⊗ circled times = vector product
⊥ up tack = orthogonal to = perpendicular
⋅ dot operator
⌈ left ceiling = apl upstile,
⌉ right ceiling
⌊ left floor
⌋ right floor
〈 left-pointing angle bracket = bra
〉 right-pointing angle bracket
← leftwards arrow
↑ upwards arrow
→ rightwards arrow
↓ downwards arrow
↔ left right arrow
↵ downwards arrow with corner leftwards
⇐ leftwards double arrow
⇑ upwards double arrow
⇒ rightwards double arrow
⇓ downwards double arrow
⇔ left right double arrow

OPERATORS
∀ for all
∂ partial differential
∃ there exists
∅ empty set
∇ nabla = backward difference
∈ element of
∉ not an element of
∋ contains as member
∏ n-ary product = product sign ( prod is NOT the same character as U+03A0 'greek capital letter pi')
∑ n-ary sumation
− minus sign
∗ asterisk operator
√ square root = radical sign
∝ proportional to
∞ infinity
∠ angle
∧ logical and = wedge
∨ logical or = vee
∩ intersection = cap
∪ union = cup
∫ integral
∴ therefore
∼ tilde operator = varies with = similar to
≅ approximately equal to
≈ almost equal to = asymptotic to
≠ not equal to
≡ identical to